To me low profile is a nerf that's just designed so you lose a one v one, everything else equal, with a regular profile character. It's enough to matter. It's not enough to ruin a character. The problem for me isn't that low profile isn't strong enough...because if you make it stronger, you'll nerf a bunch of characters that don't need nerfing right now.
What you really seem on about, OP, is I think wraith. Who is a common complaint because her size is really small compared to other low profile characters.
Seriously, characters like Octane and Wattson do NOT need more nerfs right now. They need buffs. So making low profile more severs is not the best idea, imo, for solving the problems with characters who just have really small hit boxes.
If anything, you should make another trait called 'very low profile', give it to wraith and make it like -10% damage. But if you do that, you better bring back some of her abilities because they're pretty bad right now.