Try out the SCSS syntax (or LESS), might warm you up to it a bit more.
In the end I find that if I organize my CSS well, changing things like colors really isn't such a big deal. Like you say. Find/Replace.
Oh well. Either it will pass as a fad or I will one day be forced into the light.
I strongly advocate giving the SCSS version a try. It's straight-up CSS with all the things that should have been there in the first place.
In the situations where a designer provided .psds for me to transform into html/css, no I haven't had to modify anything. But then, the iteration on the design happens with the other guy, and he does it in photoshop. If a change happens, he just sends me the new asset images, and I just replace them in the repo.
The times where I'm the one doing the design work, I end up switching things up a lot. This is because I don't do my design work in photoshop, but rather in the browser with actual html/css. So even while I'm iterating on something by myself (before having even shown the client anything), I'll switch colors up constantly trying to get something I'm okay with.
Rather than trying to remember a previous hex, or looking it up, you can think ok, this should be the darker highlight colour - and as you say, looking later you know which colour that is.
It's not just colours - a good example is a clearfix. Rather than add it to the markup, you can add it via css, and of course if you change it, you change it once.