I see both sides of the discussion. However, I think we can be thankful in knowing that we'll be able to count on gameplay being improved regardless of which teams are going to be included this year. The actual gaming aspect
is going to be better (barring some weird ESPN NBA Basketball 2004 disaster). And I also believe there's no chance current teams and players won't also see large improvements (we've already heard about Dirk's rumored aesthetic and signature upgrades).
So therefore, I'd treat the classic teams as additions to product rather than a direction change. I don't think anything's going to happen where 2K is going to be like "Well, we didn't really touch the 2012 Pistons because we decided to focus on classic teams instead." I think it's rather going to be "We made our game awesomer (yes, awesomer) in more aspects than a lot of people were expecting. Instead of only making fans of the current league happy - or fans of the past - we decided to spread our wings as far as possible."
I think a change of direction would be Nike stopping their shoe production and focusing on basketball shorts. Instead, they just kind of branched out to appease more folk. 2K's not eliminating currents, they're just willing to appease more folk, and that's awesome to me. On top of everything else, it was likely a safe bet for these guys to go retro this year with the lockout looming about. It's a solid business maneuver.