Yeah, I've warmed up to ABBA a lot as well. Doesn't hurt that those gals had actual voices, and autotune wasn't used to massage every song into digital, cold perfection.
Conversely, some songs and bands I thought were sooooo awesome when I was a teenager I've sort of cooled off on now. Roxette, for example. Loved them. Now I realize how generic and uninspired they were in many ways. Not bad, but not worthy of the amount of music worship I gave them when I was thirteen.