I'm seriously thinking about making active, following companions vulnerable to radiation this time around in fallout 4. It's weird, bringing them into the glowing sea without protection and they're fine. I may try to use a variant of amazing follower tweaks to make them automatically switch to radiation gear in certain cases. It bugs me and my immersion that piper will complain about radiation for instance, but I can wander through the radstorm and she's invulnerable... despite the whining.
Assuming that I'm successful in this endevour, other than making my game harder and less convenient, am I missing anything?

It sounds like a good idea. The one thing that bothered me in Fallout 4; is that you have to wear a rad suit or power armour to traverse the glowing sea, or you would die. Meanwhile your companions can run around in their starter gear with no problem. For role-play reasons I always make them carry a rad suit when we near the glowing sea. It would be good if someone could make a mod that would make them auto equip rad suits.

Amazing follower tweaks already auto-changes gear for almost everything under the sun, even swimming... but, as far as I can tell, not radiation. So it's possible, but has been overlooked so far, sadly.
Once in a while there's items that are near a very radioactive spot. Rather than irradiate myself, I realized I could order companions to pick up the object, unharmed. Its... seriously immersion breaking for me, despite the fact that fixing this would be a lot more inconvenient.
I get that all the other npcs had to be made rad-proof because they're too stupid to run for cover, but that's still something I would have loved to see.
(Yeah, it's unpopular, but I wish the rad-storm damage was based on being directly hit by the rain rather than the lightning flashes causing radiation, but it's been argued to death futilely in like a million posts by others on the nexus. Too many people want it left as is, it seems.)