Pre-post caveat...I'm replaying to this thread after some 11 pages worth of other replies, none of which I've read, so the following is in no way a response to anything above other than the original post.
I don't entirely understand MMA, I don't follow it or watch UFC and all that, so most of what I know about it is second hand knowledge. But I value mixed skills. I've crosstrained off and on through the years - on more often than off, basically, whenever I've had the time and money - and because of that I find the idea of being limited to a particular style, well, limiting.
On the other hand, I started out in, and spent six years in, an extremely traditionalist Goju Ryu dojo, and while life has since led me elsewhere I am "by birth" a traditionalist. But while I was kind of good at that, it turns out that's not really the environment for me, and time led me in a direction I doubt that original Sensei expected (and definately didn't like). There are a whole lot of reasons why it happened that way, not all of which I've worked out yet, but at the most basic level I am far more interested in surviving a fight than I am at being a proper goju-ka - whatever that even means, I'm not sure I even know anymore.
Frankly, I'm the kind of person for whom practicality is always going to win out over tradition - if I can use it, it's golden, wherever it comes from. I suppose in that respect I don't really get MMA because there are rules, and I'm all about living through being attacked by someone who actually wants to hurt/rape/kill me, in other words, situations where surviving is the only rule. But the "drawing on everything" aspect of MMA makes perfect sense to me.
But then there is the spiritual side of things, which is the one thing that draws me to traditionalism. I am not an overtly spiritual person, and if you don't know me well (or read the crap I post here) you would never even know I even think about such things. But I do. I got a lot out of the traditional training, and I would never say otherwise, but I reached a place where there didn't seem to be anywhere else to go, technically or spiritually. While my primary concern is being able to take care of myself in a life-or-death situation, I also want to test myself and push my limits in the mental, emotional, spiritual sense. I suppose that also has its practicality. Survival isn't just about being alive, afterall.
One of the most limiting things I found about my early training was that it always seemed that spiritual battle with my 'self' was only legitimate if it was occcuring within specified paramaters (I suspect this had more to do with my instructor, well-meaning or not, than with Goju itself, before anyone jumps down my throat!). Essentially, it felt as if my life outside the dojo meant nothing in the grand scheme of spiritual growth, as if it didnt count unless it was supervised. And you know, that to me was the most ridiculous damn thing...you can't prescribe spiritual growth.
So do I think MMA has helped or hurt, or that it's irrelevant? I really couldn't say. I've been doing this for seven years, so while I'm certainly not a beginner, I've only just scratched the surface. I am also wary of lumping all the arts in together. MMA is one thing, and all the other arts are, well, whatever art they are. Parts of each may be used in MMA, but they are not MMA, and MMA is not them, and so far as I can tell they are all alive and well in their own right. Okay, that whole sentence says a whole lot of nothing, I know, which is maybe my point. The popularity of various martial arts comes and goes. Eventually MMA's popularity will decline, and something else will take its place, and while the landscape may be somewhat changed I don't think we can really say it will be better or worse.
Evolution happens whether we like it or not. If it takes a slice out of the traditional arts, then perhaps that is something to mourn. There is value in preserving tradition, and it is always sad when such things disappear. But perhaps this tradition we ascribe to them is more about glamourizing them than about reality. Martial arts are, or at least were, at their inception, about battle, about surviving that battle, about getting the job done and getting home at the end of the day. If MMA is about using all the available tools to succeed in battle, real or staged, is that really contrary to the spirit of martial arts?
I don't have the answers to these questions. I have some opinions, but they are in no way set in stone...I've been doing this long enough to know that I don't know a whole lot. I suppose this post is more me thinking out loud than anything else.
Osu.