That's seems like a good Reason why there isn't a restricted full Respec.
Why isn't there an unrestricted full Respec, though? Is it really better for the Story, when Players use Mercs because some of the Companions are just plain terrible build?
Their builds are tied into their stories, yes. The team believes that altering them has a negative impact on immersion.
If you want full control over your build, you can use mercs, or if you are adamant that you need this and it won't affect your experience, I believe there are mods that let you accomplish that.