Its still considered pestering someone if you send someone a billion messages asking/begging for characters. Even if you do use the word "please".
Adding more characters takes time and effort and the guy pretty much has had very little sleep or time to himself for the past years (from what i read) throughout making this game (which looks terrific and has a good roster). he deserves a vacation and not to have to go back to work just cause some fans are being whiny babies.
If you want Mewtwo to be in Smash, go make your own homemade game if you got the time.
If you're going to develop a game, then you also need to take into consideration that people DO have a say in the matter. What would be the point of spending years on a game and suiting it to what only what YOU want in it? Nobody would buy it!
Sakurai deserves a vacation when he knows he has done his job right. People are going to be disappointed one way or the other, but bringing back Dr Mario over a character like Mewtwo is pretty ****ed.
You seriously cannot just assume that people aren't going to backlash. We have the right to be angry and put in a say. You might like the roster, but it's not the same for everybody else.
FYI, Mewtwo was already brought back in a fan-made game. It's called PM, go look it up and refresh your memory if you've got the time.
If you couldn't care less about it, then why are you even bothering to come here and post?