I totally agree. He was doing it in plain sight, everyone who witnessed his games had equal opportunity to use his approach but they didn't until he was leaving them for dust. The same will be true for current great players (incl. Magnus Carlsen and others) and chess knowledge is bound to evolve. Eventually, perhaps, our chess knowledge will be indistinguishable from that of computers and the game will lose all it's interest to us. But so far this has not happened and we have a great theatre for one tiny aspect of the human intellect to play out on. Let's enjoy it while we can.
There's always rapid and blitz time controls, where you can't prepare and calculate like that. I know that to a lot of people it's just worse chess, but I think that it's the future of chess as classical OTB becomes more and more ossified from engine analysis.
I don't like bullet, but 15-minute and 3-5 minute chess is wonderful to watch.
I love Tal's games, and you can learn a ton from them - but it's undeniable that he played pretty inaccurately even for his era. Most experts understand it, respect Tal for who he was and what he brought to the field, but caution younger players from emulating him too much and instead to study players way ahead of their time - especially players like Paul Morphy.
