Here is my viewpoint on the entire Smash 4 debate.
Smash 4 is a new game, and there is still much to explore. I think it is pretty clear its staling process will happen faster than Melee's, but right now that is not something to worry about. But in the future, that could hurt Smash 4.
I think the Diddy hate is an expression of how the Smash 4 community doesn't believe in its own game. Could you imagine Melee players hating Fox the samy way?
It probably won't happen. The reason why is because the Fox matchups can still be interesting to Melee players even if already seen X times. If the Smash 4 community doesn't feel that way about Diddy Kong, the game won't have that much of a future. Why? Right now Smash 4 relies on being unexplored to make it fun for the viewers and Smash 4 fans. At some point, some characters prove to be better, and if the game is patched, there will be hate for other characters... For a game to be loved for a long time, it needs to be good enough so the community isn't bored to see the same matchups all the time, and if that is given, every variety on top of it makes it even better. But if the depth is missing, it is only a matter of time until the metagame is "used up" and the game is getting uninteresting.
Being new doesn't necessarily mean that it can't be flawed.
Now to rant on a few fallacies:
What is this "winning by other methods" I see everywhere?
What is wrong about using wavedashs or any other advanced techniques? This is seriously a questionable attitude towards games. I approach a game with the attitude saying everything that is in the game can be used and no method or option is defined by any quality other than their effectiveness.
What is this even? It seems to be so arbitrary to just claim a certain AT is unfair. You could say in a similar way:
Players that use approaches have no honor, they are only too bad to win with timeouts. or
Players having to use back-aerials, forward-throws or up-tilts are too bad to rely on any fair methods.
The creators' intention shouldn't be relevant when exploring the game. The game, after all, is as it is and whether the metagame developing from it makes it worth playing it competitively or not will reveal itself sooner or later.
The mod argument about PM is something I don't get either, what has its official status to do with the quality of the game? Should we care if the game is made by people in a building with a shiny company logo on it or by people in a building without a shiny company logo? I don't think so.
Many Smash 4 fans here don't know much about Melee, I think. The balance is not that good indeed, and Smash 4 can keep up with it in that aspect. The fast, "sandbox" style gameplay with the ability to do custom combos and evolve complex metagame from simple rules is what makes it truly great. PM is much better in terms of balance than both, but the matchups are currently underdeveloped, so you often see too much gimmicks and only first-level-adaptation, so that takes away from PM's current metagame and is probably why Melee has the more success.
Just recently a friend of mine who was a Smash 4 player who disliked Melee and PM a bit for their "autocombos" rethought it and now prefers Melee and PM. I think Smash 4 rather catches new playes first (more characters, newer game), and some of them change their opinion as they look at other facettes of the games.