I like your idea, there will be other stuff that you can buy different models for in the cosmetics shop (helmets, armors, etc), so why not different vehicle models? As long as their silhouette still allows for empire identification (NC's square and improvised, TR's roundish and smooth, VS's triangly and crazy) and they don't cause any imbalance (smaller hitbox, etc), i think it's fine. I know it's more work than just skins or simpler models but i think it could be worth it for them and for us.
Though it could get a little heavy for lower end PCs to load up so many different models in a huge event with everyone in their unique armor and vehicle. Hopefully that won't be an issue.
There, i posted my opinion... happy?