Obviously the message sent from the devs was that they really really don't want players porting unlimited alts by taking advantage of summoning mechanics. The message has been received. I'm sure they don't like the insta-kill factor any more than the players do, but felt there was no better way to send such a strong message - anything less than insta-death would have been shrugged off by the players who were abusing unintended mechanics.
It's possible that after the message has fully sunk in that they may relax the insta-kill by going to a new debuff on summons or something similar which would have an identical effect without the ohko, but I'm not going to hold my breath either.