Of course T-spins aren't necessary to have high level gameplay. Then again, many other things aren't necessary to have high level gameplay. Speed alone isn't a necessity to have high level gameplay. Heck, even tetrises aren't necessary for high level gameplay. T-Spins add another dimension to the game just like any other aspect. The number of dimensions determine the limit of high level gameplay. Why can't we just nerf the power of T-spins rather than taking them out completely? Rather than taking away dimensions, shouldn't we add more? It all comes down to opinion of what ideal tetris is all about. I just think that changes could be added to the formula without drastically changing it that's all.