TH level DOES matter in clan wars.
After a couple of clan wars, I have come to the conclusion that TH level DOES matter. The main reason is just for the sheer volume of defenses you can get. I don't care if you are a preemie TH 10 you still can have up to 2 IT's AND 3 Xbows. Even at level one they can do considerable damage to troops... even if you have low level walls... which leads me to point 2.
Matchmaking bases on walls is pretty irrelevant. I have seen so many balloon, dragon and hog attacks that using walls as some determiner of the matchmaking process is kind of irrelevant.
All of this is just my .02 so far from what I have seen.
Which side would you rather be on... 10 level 10 TH with level 10/11 walls or 25 level 10 th with a bunch of pink/purple walls??
I am sure they will tweak the matchmaking process at some point once SC collect all the data from clan wars but I think the level of your TH should some how be incorporated into the equation.