SE didn't switch to auto-attack just for kicks or to dumb the game down
in large part it to lessen the load on bandwidth and lag

with auto-attack every regular attack is on a timer server side
but with the old/current system you are having to send that attack to the server
the current/old system also has multiple attack types, so the formula is constantly different if you're using various attacks

this also helps player on the communication side of things, no more trying to type while missing attacks
no more loss of dps while you sit in a BR stack waiting for everyone to get in
and the best part for players, less combat lag (which you really notice in full parties in populated areas)