this argument isn't original, the answer to your question has been given many times.
legacy sucked
skill didn't matter since anyone could get rank 1 within a week
legacy was more of a beta for supermechs, it was there to test out mechanics, see what works and what doesn't
legacy was more pay to win than reloaded is since in legacy you literally couldn't get mythicals without spending real money
just because your old legacy items are no longer viable, you should consider yourself lucky you even still have them, mine were gone for good. not that I care, to be frank, since they wouldn't do me any good anyways.
reloaded was a chance for truly skilled players to again outmatch the noobs, it was a soft reset.
it is, in the end, pretty childish to assume the world revolves around you, and that the end of legacy is such a terrible horrible thing to happen in your life, as if it wasn't just a game. you say you've played supermechs for most of your life, which makes me assume you must be an adult by now. if so, act like one, otherwise, find another hobby to obsess over and continue putting yourself into this loop of setting yourself up for disappointment. times change, you either learn to live with change, or you get tossed to the side as another doomsayer nagging at people who are too busy to listen to you, as they are continuing to enjoy the same game they've loved for years already.