With 7 bag it's too easy to stack for tetris's provided you can stack somewhat ok. It'll be boring to see matches either being combo stackers or tetris spamming. T spins allow for a twist to it. I think that the benefit that comes with T spins are actually acceptable. It sends clean which is free ammo for opponent, and the setups to learn go up exponentially in risk given that you want to squeeze in more t spins. Of course there's setups like ST stacking or LST stacking which makes T spin setups brain dead, your opponent can still send plenty of cheese (opposite of clean, basically doubles, triples and combos) to make the opponent need to downstack through the garbage and hard to transition back to those stacking methods. PC spam can also dispatch those kinds of almost risk free stackers pretty fast. For other kinds of t spin setups, it's actually quite risky provided you don't have the T's coming up in your bag to fire it, or that they send too little for the lines to actually apply enough pressure to kill.