jpeg wrote:Having different time signatures is defo a feature that should be present; however it appears that 2/4, 4/4 or 8/4 are the most comonly used for most modern musical styles.
Much of modern music is also made by minds that believe it has to be 4/4 or people simply will not buy it. And sure, it may not be all surprising and a few eyebrows raised, if, for example, Iron Maiden were to release a single with a waltz on the A-side.
But all of this is a matter of expectation. If nothing ever changed much, we might still be clacking rocks and have a few samples of grunts to boot. No time signatures to worry about.
jpeg wrote:The odd signatures are seeminly for more arcane styles of music, like folk, waltz or other less popular ethnic styles.
That probably depends on what kind of music one has an interest in. For example, one of the song makers from Abba and the music for Chess, travelled around in Sweden and played folk music for his peers (yes, old people). So sure, it may not be mainstream, but what was your point? I mean, this guy may be old, but he understands it and he also makes "modern" music. Perhaps not music that you would listen to, but, nonetheless.
Personally, I simply enjoy using various TS for making new styles of music. I have no particular interest in say waltz per se, but I think there are interesting rhythms made, and to be made, in 3/4 TS's.
jpeg wrote:But it does not really make the music sound different per se; as u will still sound lik every other waltz or ethnic peice of music regardless
I strongly disagree with this, but that's how you see it.
However, I'll bite, going all the way down that rabbit hole, which then means that all modern music sounds the same then, I mean it's more or less 4/4 we're talking about.

Often music one has little or no interest in, sounds the same. I get it. But this is true for ANY music, not just odd styles of music. Just because a music style is old, does not really render the time signature old. Lots of modern music serve as evidence.
To me, country and western, as an example, and I am referring to the "mainstream" modern kind, all sounds the same. I am not saying it's bad in any way, just sounds bland to me, but that's because I do not like the music, at all.
3/4 may be called waltz time and may also sound like... waltz, but waltz is not the only kind of music you can make in 3/4. Waltz was simply an example of a type of music you can make with such a TS.
---
I may seem concentrated around 3/4, not so, it was just for purpose of discussion since that was already on the table, but I think absolutely any TS is fair game. Be creative!!!