I doubt it would have lasted as long. I heard somewhere that the original plan was only for 3 seasons and that Twilight becoming an alicorn was supposed to be the end (no idea if that's really accurate, though I could easily believe it). Now, it may have gone on past that a bit without bronies, but 8 seasons? Eh...8 seasons is a really long time for any "kid's" show, and bronies sure do have a lot of buying power for things like toys.
For me personally it's a question of cosplay. I find ponies really easy to cosplay because when you translate them into a human form there's a lot of leeway, without the self-pressure to get a costume exactly right. My life would still probably be fine without it, but it is fun to have finally assembled a few cosplays that I actually like.