If you play on a dead server (which will happen in Classic also), modern WoW still allows you to use the Communities feature, the friends list, the forum, etc. Classic doesn’t have any community features or tools that retail doesn’t also have.
Its main advantage right now is that it’s “new” and that people who play it see themselves as a separate and superior community, which at the core is the source of many social problems, because this same mindset will lead to the eventual exclusion of people who don’t play meta classes or otherwise don’t “fit in”. This happened in vanilla too once the game had been out for a while. The elitism was very strong back then, to a point where some people were socially ostracized and driven off the server.
None of your points are limited to Classic. In retail, if I want to do normal EP because my group now only does HC, I can find others to do it with. Not just during prime time, but pretty much at any time. Same with M+, PvP islands, arena, rated BGs, etc. In vanilla, a year in, all leveling dungeons were dead on my server, you simply couldn’t find a group. In retail, you can always find people to do something with – and you can befriend them and play more with them, just like in Classic. Yes, people grouped for 3 minutes to kill an elite, just to disband again and likely never see each other again until they made a social effort. The same social effort needed to make friends in BFA/retail.
Classic forced social behavior (to a degree) because there were no alternatives. You were social or you were excluded. In retail, you have a choice: you can be social and probably have a better time, but you don’t have to. You still have LFR and other automated matchmaking systems, so if you’re an introvert, have social anxiety, play in the off hours, have a baby or are a caretaker and need to step away from the computer unexpectedly often, you still have options.
I just don’t believe that lack of choice makes for a better game or for a better, more diverse community. If the “one choice” of Classic works for you, you’ll flourish socially. If you don’t fit in, too bad, you’ll probably be excluded from the active community. If you do fit in, you probably never had social or acceptance issues in retail, either.
No disagreement here. I’m equally sure it can drastically change lives and behavior for the worse. I’ve seen people completely drive their lives into the ground in vanilla or become total jerks. If they were leaders of big guilds, they got away with it too because there wasn’t much choice for others. The very community aspects that you praise and cherish are also fertile ground for many unpleasant social developments, like feuds, gossip, ostracism, elitism. And it’s much harder to escape them than in retail.