Why do people hate Bird's opening?

Tpr its playable and despite winning against kramnik with it is no small thing, it doesn't mean its good. But if one of those players says it in words, it would be something different. Btw was it a blitz game?

1. Nc3 d5 d4 Nf6 Bg5 this variation is popular
1. f4 is popular
first move advantage
1. e4 ,d4 ,Nf3 ,c4 ( most popular choices ) ,g3,b3,f4,b4,Nc3 ,e3 ( systems),d3 ( transportation other openings)
other choices
a3,h3...
only 1. g4 move is worst for white
slightly worse moves 1. Na3 , 1.Nh3

#5

I 100% agree. I personally play both since I know all these theories about the From's from White's perspective, why not use it as Black?

I don't put much stock in database statistics (percentages won/lost/drawn). I think they often say more about the players playing it or the situations they play it in.

For example, the modern defense has good stats, but it isn't that good. Also, some queens gambit openings have great stats for white, probably because a lot of novices who don't know how to play against d4 lose with them.