I actually like this idea for a couple reasons.
#1 it would give the ability to have anyone you wanted hit, no matter what, when, where, why, gang affiliation, wtfe you want to put there.
#2 Credit prices might go down if someone wanted to keep someone in the hospital bad enough. Edit, as G2 says above
#3 The fact that you could get hosp'd for backing out of the hit is a nice twist to keep people from just price checking...someone would really have to WANT that person hit to go through with it and not wind up in the hospital.
An interesting thought that I've had about this, and it's kinda wack but would be cool IMO:
Bare minimum of 500k puts XXX player you want hit in the hospital for 300+ mins, no way of stimming out.