Now, this is what I would call grasping at straws.
You are right, whether improvements to the IDE are reason enough to upgrade to a new version of Visual Studio is not your call. Let me tell you, I have *never* seen any C++ team to upgrade on that merit alone. Never. The compiler and the tooling were *always* what the upgrades were all about.
Now, this is a big world, so I am sure you will find some developers who wouldn't care much about the compiler and would upgrade just for the IDE. But you'd be hard-pressed to show if this type of behavior is at all typical. We are not exactly newbies here. We do C++ for a living, did it for umpteen years. The compiler and the tooling always go first. End of story.
That might be true for you, but it's certainly not what I've seen in the several companies I've worked at.
Developers where I've worked have cared more about intellisense working and being able to use new tools like WPF and static analysis tools to any 5% improvement from new and clever optimisations in the toolchain.
I've even worked at a company where they used VS just as an IDE, and toolchained to GCC because they were compiling for Linux, but wanted intellisense. So I'm not going to buy your "We only want a command prompt, the IDE adds nothing" argument.