Hi Karen
you asked me why modern characters don't have the lasting appeal of Looney Tunes and Hanna Barbera characters.
You said that even though some of your movies have made money, the characters don't seem to outlast their initial stories. In my opinion, that's because modern movies focus more on "the "arena", the formula animation plot and the special effects but they pay very little heed to character.
Characters that are charismatic, unique and engaging can fit into any "arena". Iconic classic characters appeared in different scenarios all the time, and the audience never questioned it. In fact they looked forward to seeing their favorite characters over and over again. What made these characters iconic?
I'll give you my theories. First of all, there is no one quality that makes an iconic character. There are various ingredients that go into it and not each lasting character has all the ingredients.
One ingredient, I think is the most essential (to a cartoon or film character):
The Look - the individual character design
A character has to have an automatically recognizable and appealing look, even if it has nothing else.
You have to want to wear it on a t-shirt, just because it looks so nice.
It should make good toys.
Most of today's characters don't have distinct looks. They are semi-realistic and have no strong visual statement. No conviction to a design.
This stuff looks like it was designed for a 1985 DIC show.
Modern characters are generic to look at - some are even proud of it!
Do these look iconic? Do they make cute toys?
If you saw these in the supermarket, would you know who they are? Or would you just say "Oh, there's a lumpy turtle! I'll get it for my niece Tabitha."
The Voice
Having a distinct cartoony voice adds a lot of instant appeal and recognition to a character.
Acting - Baby Bottleneck
Uploaded by chuckchillout8
It used to be an automatic requirement for cartoon characters to have strong distinctive voices. That's why cartoonists went to radio to find stars who made their living on their voices and acting alone.
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Uploaded by chuckchillout8
FF03DoesBarneyKnow
Uploaded by chuckchillout8
Too many of today's cartoons use "star voices" which sound like no one in particular. If a cartoon character sounds like your next door neighbor, then he doesn't sound special or unique.
Here, turn this on, close your eyes and just listen to the voices. Doesn't it sound like your next door neighbors trying to solve a community problem? Can you tell one character from another?
Most characters that have lasted decades had strong distinctive character voices.
The Personality
Strong personalities like Bugs Bunny, Daffy Duck, Foghorn Leghorn, Yogi Bear, Jinks the Cat seem real to an audience and therefore stand a chance of lasting a long time.
WB characters don't have quite as distinct character designs as some other classic cartoons, but they have really distinct voices and personalities.
Compare these personalities to say, Droopy (who is in some great cartoons) or any characters in feature animation today. Modern feature animation characters have completely stock bland personalities. Every movie uses the same characters. The bland lead, the tough feisty woman, the gay villain, the obnoxious sidekick etc... these aren't unique individuals, because you see them all the time.
Uniqueness
A unique character has to be surprising, something you don't see every day of the week or has a combination of incongruent traits that add up to magic. They can have some traits you identify with, but can't merely have standard traits if they are to stand out from the tons of forgettable stock animated characters.
This uniqueness should reveal itself on as many levels as possible: the look, voice, personality, and movement.
Many WB characters have all these traits in one character.
The character that is the most unique ever created is Popeye.
He is a bald old man with one eye, no teeth, scrawny except for bulbous forearms and calves. Despite being old and decrepit looking, he is the strongest man in the world and loves to fight. He gets extra strength from spinach.
He is ignorant and has a completely unique made up dialect and voice. 
He is low class yet has great nobility.
In today's environment you could never sell a character this unique with so many odd traits, yet he is one of history's most famous and popular characters; purely American during America's best period.
Character Chemistry With Other Characters
A character doesn't exist by himself. He has to have other distinct characters who together create sparks and chemistry. When you have this type of clear entertaining relationship, the stories write themselves.
So those are some of the ingredients that go into making characters so strong that you can make many stories out of them. They don't have to die after the first blockbuster weekend that doesn't make enough money to pay for the cost of production and marketing. Real star characters go on to make money for decades after their initial introduction. Why? Not because of the "story". But because people love the characters. The stories are written around the characters. This is the opposite thinking of today's "Create an arena and then stuff it full of characters that fit it."
But the most important ingredient in a star character is not the character himself or even any of the parts that go into it. The secret magical ingredient is the creator who understands character and chemistry. This ingredient is the rarest of them all.
I can explain to anyone conceptually what makes a good character, but that won't make it any easier for the listener to go ahead and start creating them.
You could know music theory and still never be able to come up with memorable melodies. It takes a certain kind of talent who can create melodies - not every musician can do it, even if they are virtuosos in other aspects of music.
The same thing applies to creating characters and being able to bring them to life. You have to just naturally have a feeling for character and gripping situations - and you have to have enough experience in your medium to know technically how to pull it off.
In live action, the actors themselves are the characters and they make it easy for the director by bringing their own custom made personalities with them.
In animation, you have to be able to put yourself into the heads and hearts of many characters and that's why it is such a rare talent and not many animators can do it without a good director.
That's why these shorts programs are so crazy. Modern TV execs think that anybody can create characters and it's just a matter of luck until one comes along, so they try out anybody off the street and waste tons of money, instead of finding someone who actually has the talent and letting him develop it with a crew over time.
That's what Leon Schlesinger did at Looney Tunes. He found and nurtured the best cartoon directors in history. He let them experiment; they tried out lots of characters, honed their skills and they ended up creating more popular characters than anybody else....and made a ton of money for Warner Bros. for 60 years.
It's not enough to have great characters; you have to have great directors who know how to bring them to life.
How many horrible Bugs Bunny cartoons have you seen made in the last 25 years? It's not easy to keep characters alive, no matter how great their raw material is. You need the great director who understands character and uniqueness. That's the most important ingredient to lasting characters.
BONUS TREAT
