So just to look at the example proposed of 2 WAR walker vs 2 WAR power hitter first we need to realize that a 2 WAR hitter (who is average defensively for the sake of argument so all his value is from his offense)is not a good hitter. That hitter is essentially average.
Jonathan Schoop, the 2B of the O's, is a great example of a 2 WAR power hitter. He was average on defense and had 25 homeruns. His slash line was 267/298/454 - 752. Should be obvious that for an average hitter if you are going to be beasting in homers then your walk rate isn't going to be great.
Now I couldn't find a 2 WAR walker who played average defense but Brett Gardner fits the bill pretty good of an average hitter who has low power and walks a good amount. He did have 2.4 WAR this season but that's because he's a plus base runner. But his hitting was average and that's what we are looking at. He had 7 homers this year with a slash line of 261/351/362 - 713. As would be expected. A high OBP with little power.
Running the numbers through
http://www.baseballmusings.com/cgi-bin/LineupAnalysis.py
A lineup full of Brett Gardners gives us 4.48 runs per game. Replacing one of the Gardners with Schoop's numbers gives us 4.51 runs per game with the optimal lineup.
So all of a 0.03 runs difference per game over a full season which comes out 5 runs. So replacing a team full of walkers with 1 power hitter doesnt do much of anything.
Granted there is going to be some variance here as the OBP/SLG numbers used aren't park adjusted. But the point should remain. If you have a league average hitter and replace him with another league average hitter. You are going to score the same amount of runs regardless if he's a masher who doesn't walk or a guy who gets on base a ton and has zero power.