Wow, that's great. I'm adopting that. Musical means to sound like music, not like a speaker. Cool.
That's one possible definition, but the usual adjective for this around these parts is "transparent," which is defined more consistently, I believe. "Musical" is typically used a different way, at least from what I've seen over the years, and if people are all using their own definitions for a term, then it really means nothing (besides a generally positive description, but even then it could be a euphemism for inaccuracy, and I've seen some instances).
From a design standpoint, there are pretty stark differences between a speaker that was designed to be a musical speaker, and one that is designed to be a home theater speaker. I don't think I've ever heard a speaker that excelled at both. The Paradigm Studio's that I own are probably the best compromise between both, but there are a number of much better musical and home theater speakers out there.
Your point is well taken regarding the trade-offs between accuracy and sheer output, but this is yet another definition among many.