I understand the argument - from both sides, and I can't say I like either option. On the one hand, tying our hands behind our backs in a knife fight is a losing proposition—If the goal is beating your opponent.
If you're worried about keeping the respect of everyone else, it may be the only way to go. I think (yeah it's just hunch, no actual data to work with) that the average American is disgusted when the left does it and shocked and disgusted when the President does it.
Perhaps the correct approach is to use shame rather than insults. Sure the left has no shame, and they won't care. But the point will be made to those not yet fallen to the moral relativism of the nihilistic left. It will show them what they're fighting against. It's certainly the harder path. Pithy one-line insults are much easier to construct than pithy one-line moral aphorisms.
The insults obviously get under the skin of the leftists. It's why their reaction is so vitriolic and hypocritical. There is a visceral pleasure in subjecting them to a bit of their own. I get it, and I've done it. The question is: how does this play with the average voter. The average voter still thinks in terms of Republicans and Democrats - when what we've got are Democrats and Progressives. Left of center vs. crazy. When I look, I can find maybe a dozen genuine Republicans (small government) in national politics. The sides seem to boil down to Crazy Leftists vs. Anti-Leftists, not as most people think - Left vs. Right or Liberal vs. Conservative.
So, is the goal to feel better because we slapped them silly when they deserve it (most of the time) or is it to increase the base of anti-leftists.
I'd love to have a way to increase the actual number of conservatives, and I think the pendulum has begun to swing in that direction. It would be useful if we still had some conservatives left when the pendulum gets that far.