there is no planned “end” to SR. Well one can say that SR50 is the planned end “lore wise” and I think most ppl can do that with just basic knowledge of the game and reasonable itemization and skills. But still, end game should be for those who really wanna learn about the game and get better. If anyone could do SR 50 with just playing blind, I would not play this game - it would be too easy for me.
Remember that the devs are ARPG nerds themselves and like the old ARPGs. Do you remember when you hit Hell difficulty in Diablo II? Took me a looong time to figure out how to beat the game at that difficulty. Was it worth it? Yeah it felt like an accomplishment, that I have done something others and myself have thought was impossible (but that some think it is rather trivial once you know basics of game mechanics). Progression in other words. Just like math, for those who wanna solve Einsteins equations for general relativity and just not read about it in popular science magazines - you have do the the hard work, fail number of times and then eventually succeed.
Can you give an example of this? Where a game change was forced upon just because a few min-maxers broke the game that destroyed the game for casual players?