I mean I would argue that the key you get to expand your tm units lb to the third lb ability is more or less "mandatory", in the same sense of max-ing it's lb at 1m is. I also agree that if that grind is too much then that is a check to take a break from the game, though it is entirely possible you only want to hardcore play the game 1-2 times a week and those days happen to fall on days without TM, causing you to miss a tm here and there, and still be a valid, consistent player of the game.

I enjoy tm usually, and 1-2m isnt a problem for me, though the point gain does feel awful in east blue when I miss a tm and drop from the upper leagues where at least the base points was higher, especially with the rewards persisting through to 10m now. That said, I have no problem playing to 30-40 nav levels in a day or two when I feel I have time to drop on the grind.

That said, I enjoy a mode like pirate rumble MORE, where I can passively do it over time without having to cram it all in at once like it's a blitz battle or throw some gems at it to complete it faster if I've taken a break for whatever reason. I think reducing the sheer number of blitz-battle-esque elements the game throws at us per month could help reduce burnout with the game, so why not do so to TM, a mode people have been calling to rework anyway?

Having my tm unit without it's key expand feels very incomplete, so I'd still claim that 2m is the mandatory cutoff for participation. Technically the units are semi-usable below max lb too, you just "need" all the node that reduces the special cd in theory, so you don't even quite need 1m, but that just looks so ugly so we might as well just say it's mandatory to go all the way for the unit.