I mained SCH in 3.X but switched to AST because I wanted a challenge when healing.

It wasn't that SCH didn't have a high skill ceiling. It absolutely did. It's just that the class was basically impossible to screw up with (unless you were doing savage content or something). AST could go OOM in seconds (and kinda still can if damage gets bad and you don't draw enough Ewers), but 3.X SCH could fling gobs of mana at the boss with both hands and never have to worry about it.

That said, the nerf in 4.0 is absolutely overkill, yes.

It's strange: the dev team nails it on some classes but fails it on others (mainly WAR, MCH, and SCH).