Hiltslashing is painful because it is easy to pull off and breaks the combat rythm. Breaking the combat rythm is a good thing, as long as it doesn't turn it into a totally depthless random rock-paper-scissors game a-la "you hold/feint, I spam, I win - you attack normally, I spam, I lose", which is the case for hiltslashing. In the end, fighting hiltslashers is just a matter of knowing who are the hiltslashers in the first place, and play accordingly ( that is, blockblockattackblockblockattack and forgetting about doing interesting things like feints and holds ). I think hiltslashers are boring because they force the opponent to be uncreative, make the outcome more random and draw duels for hours.
Removing it altogether would actually speed up my combats because I wouldn't need to switch to Urist mode.