I have to disagree.
Like any job, if you know a boss will go invuln soon and you'll waste your big attack/procs/song/whatever, it might be better to hold it, or realigning or using it differently.
While I understand what you're talking about, I think Dancer is already a easy job and doesn't need more adjusment.
And giving the ability to froze your proc when dancing while it's about priority isn't fair for others jobs who also have priorities and proc to deal with.

Depending of the encounter or the situation, you just need to adapt.