Just like all the third/fourth/etc kits in MLB/NBA/etc...money, money, money.
I think the thing that is a pain is most of the MLB, NBA, NFL teams have some sort of defining see-able symbol ... Steelers' logo, curly W, NY, Laker, etc. on their uniform/hat/helmet when they play. Where as the Premier League teams have everything but the logo in plain site. I could tell it was Liverpool by the Standard logo on their chests. Then, up in the corner is the LFC logo on a black jersey. Anyway, that's my rant. I'm done.