I think it depends on the circumstances. I've been on the giving and receiving end of what you're describing, and there are times when it's not really an issue, and times when it gets to be an issue.
In mixed, I almost never go at the woman at net, even at 8.0 where it's more acceptable. If you're at a level where you are able to put that much stink on the ball, you should have another shot on that type of serve. If you're hitting the ball that hard and don't know where it's going, then you have no business hitting it in the first place since it'd be too easy to actually cause injury, and even in USTA league, it shouldn't be that serious.
I had an incident last year in a 4.5 men's match where a guy got very upset at me for pulling a serve up the line at him, and later remarked to a team mate that I was a "headhunter." The truth is that, while I had other options, his partner was easily the stronger of the two, so my best play was to make him hit a shot. I missed my spot (was aiming for the alley, not for his bellybutton) and had no intent in pegging him, and we made nice after the match, but he was clear that he wasn't happy at the time. I think that if I had done it repeatedly, it would have made a tense situation even worse.
I still will pull returns up the line, but more often than not, I'm not going at the netman but rather trying to put it in the alley and make them play the point off balance.
Back to the Prestige MP. Should have never deviated.