You kinda hit the proverbial “nail on the head” when you said : most destruction, most activity, most characters online, most satisfaction. Those things do go together.
I know people are focusing on their own peeves now, alphas, chat bubbles, whatever, instead of focusing on what made the environment “the sandbox” supportive back then, and most importantly what changed on the largest scales, cause it isn’t alphas or chat bubbles or anything like that that prevents the scales of all that destruction, satisfaction, etc.
Its cap proliferation (now + citadel proliferation) and bots. The bots in all forms that just add to that cap proliferation. Where are the days when 10-20 battleships could take out a fleet of 300+ in null sec ? Why can’t it be done now ? These are the questions you need to ask yourself. Where are the tactics that let lets say 10-20 ships take out 300+ carriers due to superior tactics and strategy ? Where is the balance now ? What happened to it ?
Add to that the ever increasing armies of ratting and mining bots to support the above and the game is getting really screwed.
Alphas had little or nothing to do with it. Neither did chat bubbles or other sort of inconsequential changes. Restore the balance to the game, narrow the power gap between vets and newbs to what it was back then at the height you mentioned, limit the cap powercreep, kill off (perma ban) bots, and leave the newb helping stuff in place. And once the destruction picks up again and there are some actual REAL wars instead of these sorry ass skirmishes of today, watch them all flock to it. You won’t even need to go recruiting, recruits will come to you.