I’m also noticed that old rules that I used to really, really enjoy and that I decide to now play or re-read in a fit of nostalgia, are AWFUL. I really wonder what I used to see in them! It is certainly isn’t because I’ve become an old fart!
For myself, I played the Bruce Quarrie and the Newbury Napoleonic rules when I was little (it was what my club played). When I tried the Quarrie rules again in 2007 when I was getting back into the hobby, I realized that there were just too many areas that mechanically didn’t work very well, or were slow, or I disagreed with the assumptions about them. Curiously, the other rules I played at the same time were WRG 1685-1845 which I think still stand up reasonably well.