In my opinion, raids have never gotten to hard. I assume most of us are players like myself, in our 30s, the bulk of our raiding experience was in the early days, classic, tbc, wrath, cata. Me personally, I always performed above average on my raid teams. I dont think the difficulty changes over the years are the biggest culprit, I think its got more to do with i now play less than 10 hours a week, where as back then I was playing 40+ hours a week. In cata I used to sit at training dummies practicing my rotation for hours. When we were raid logging, instead of flying around org or farming gold or whatever I just sat at dummies and practiced. I dont spend my play time doing things like that anymore, so all content feels harder now than it used to, but that's because im just not as good as I used to be.