I think the reality is that guys who have power and don't strike out are just really good hitters and having really good hitters makes you a better ball club. It's not as simple as adding a bunch of high ISO, 30%+ K rate guys, nor can you just add a bunch of Ernie Clements. I can see it both ways. Those high K rate guys can be streaky and you just need them to get hot at right time and rip some homers. Instant offense with one swing of the bat can be huge. The downfall is the pitching is better in the playoffs, so that 30% K rate likely increases to 35-40% v. top pitching every night. If they don't get hot, they kill your chances of manufacturing runs and the swing and miss reduces the BABIP possibilities.
On the flipside, if you have guys that put the ball in play, it gives you a chance for the BABIP god to shine down upon you. It also gives you the opportunity to manufacture some runs or score in errors and such. But again, that's harder to do v. top pitching every night and with this approach, you may still need to string together multiple hits to score runs (although perhaps the increased bases and resurgence of the SB will help counteract this?).
I'm not sure there's one definitive answer...