I think it's absolutely necessary. Many large contractors who don't get M+E in 3D have their own modeling teams to build a full model which they can use for scheduling and interference checks.
I find that HVAC engineers are often very careless when it comes to just throwing things on a 2D sheet with no regard for other systems and structures or what's happening in 3D. So you get ducts and pipes running straight through beams or lots of headroom and equipment size issues.