In local club cricket and, indeed through to the County game, getting your groundsman to prepare a pitch that benefits your own side is a perfectly normal part of the game. It's also considered to be standard practice at Test level.
Perhaps it seems odd that teams playing at a neutral venue should be able to do the same thing but it simply adds in the extra 'home' or 'away' factor that applies throughout all other cricket.
Also, while the Super 10 stage might have only started today, the actual World T20 competition has been taking place for a week now. Unless I only imagined this, of course ;-)