I have more issues with that sort of autohitting rather than open endedness. Autohitting takes away your control from your character especially if you know s/he can actually anticipate and deal with whatever sort of move the opponent deals. How does it feel when your character gets frozen by some dude casting a freeze spell, of which you know you can either dodge behind cover or punch him in the face before he finishes that spell? 

Open ended attacks works better imo. Of course this also has the problem of people who are too attached to their characters and/or projects a little bit of themselves into their character and takes it personally if they ever got hurt, thus leading to the absolute dodge problem.

tl;dr No thanks. Better have it worked out first between players rather than autohitting someone and have them butthurt. Open ended attack works as long as no one goes overboard with their chars.