There was a time when I would have agreed with this, but a bunch of people have come along for whom "metric complexity" is heard and felt significantly more naturally than it was back in the day when it was pretty much a 4/4, 3/4, or 6/8 jazz word. I attribute that to both the increasing "international" influence and a simple progression of musician's interests. When Don Ellis & Mahavishnu were dealing with all those weirdass time signatures, it was kinda "exotic", but several generations have had that as a part of their baseline musicality and can go there without really having to think about it.
In short, I think that any "problem" you might be experiencing in this regard is at least as much yours as it is the music's. And the reason I'm being so blunt is that I come from your generation [EDIT - More from your generation than my own as far as what meter "comfort zones" are hardwired into my brain] and still have a lot of the same issues, especially with playing in that realm. But I've heard it done often enough and well enough (in and out of jazz, as well as in and out of being directly involved in the playing) that my limitations have been presented to me so convincingly that not confronting them as being exactly that - limitations - would be dishonest.
None of which goes towards your feelings about Iyler specifically (I dig him very much, myself), just towards the general idea that "metric complexity" is a problem of the music itself. Which is not exactly what you're saying, I know, but still... if one does not allow for the evolution of genuine playing into areas with which one does not feel an intuitive warmth, then whose "problem" is that? Limitations are cool enough, everybody has them and nobody gets everything, I just think that they should be copped to as such as a sign of respect towards those who do not have the same ones we do.