This is a great idea, but I'm not sure that multiplayer would work in TomB Raider. I think it's really all about Lara.

There's those few games that multiplayer is not needed, this is one of those games.

If they were serious they would of made sure it didnt look completely like Uncharteds online

If the multiplayer is good and doesn't affect the SP campaign then don't bother trying to convince the doubters. They've probably already made up their mind.

Mass Effect didn't need multi-player, but it's actually kind of fun. Uncharted didn't need it, but it is good and gained quite a following.

The point is, focus on it being good if you have to include it, and stop worrying about doubters.