I'm not sure what benefit the preferred seats bring, apart from sitting towards the front. I don't think TK operates any form of seat blocking for Elites, and I'm guessing preferred seats will get filled up at check-in. It's often in rows towards the rear that I find myself with an empty place next to me.

But sure, a preferred row aisle seat is great for a fast(ish) exit if I'm in a hurry!