Solving the "complex music problem"?

I have noticed that, regardless of the system, simple music (i.e. music with only a few sounds at the same time, such as a solo instrument) sounds way better than what I'll call here "complex music", meaning music like symphony that has a lot of instruments all playing different sounds at the same time. I'm assuming that this is an inherent problem for audio equipment. In a live symphony, you might have, say, 15 different unique instruments (i.e. counting all the violins as 1 unique instrument), each of which is vibrating in a different way; but in a speaker, each driver might be trying to reproduce 10 of those sounds at the same time. So each driver is a single physical object trying to vibrate in 10 different ways at the same time. The result is that the music sounds muddy, all the different parts blend together and you lose a lot of the detail.

I have a number of questions about this that I'm hoping all you experts can help me with.

1. Is there an established name or term for this issue? 

2. Do you think my diagnosis of the problem above is correct? Or is something else going on?

3. Although this is always a problem, it's a much bigger problem on some systems than others. Are there some types of components, or some brands, that are particularly good (or bad) when it comes to this issue?

4. To what extent is this issue related to the components you have as compared to speaker placement and room acoustics?

5. To me, this is a huge issue. But I don't see it discussed all that often. Why do you think that is? Or, perhaps, it is being discussed all the time, but people are using a term I don't recognize? (hence question 1).  

Full disclosure, I asked a related question under the heading "need amp recommendations for more separation of instruments" and got a lot of super helpful responses. I'm very grateful to everyone who took the time to respond there. That discussion was focused on a solution to my particular problem. Here I'm hoping to have a more general discussion of the issue. I know it's bad form to post the same question twice, but in my mind, this is a significantly different question. Thanks.