@ Concepts! Your post is negative from beginning to end (despite your not wanting to sound negative).... and wrong from beginning to end...
Firstly; the comparison of WC to Steam is redundant... WC is NOT a games distribution platform...
Secondly; the quality of content/master skins is a matter of opinion... given download counts and millions of satisfied customers, yours seems to be out of place.. at best.
Thirdly; there is NO sinking ship... just a few dissenting bilge rats jumping ship... *shark bait*
Fourthly; the popularity/success of WC is not dependent on the success of XP orthe 'supposed' failure of Vista.
And lastly; who are all these smart people switching to Macs in droves? Last I saw, Apple computer sales had not risen past the 11% market share.
Quiting while you're ahead isn't the same as quiting!
Good advice.... take it.