I think (and it's just my guess) that it was an attempt to unify the look and feel between iPhone and iPad but, if so, I think a misguided one. A) because iPad is not an iPhone in form and B) because iPad has never diverged so much in other places from iPhone (dock, multitasking etc.) so it's a strange time to pick on this.
In any case, it's an incredibly minor nitpick (IMO) and it has in fact let me lay out my widgets the same on both, aiding muscle memory a bit. I'm pretty ambivalent on this one.