I will go way out on a limb here and admit that I get sexual enjoyment out of ponyplay....crazy, I know, but when I get all tacked and tied up, tongue held down by the bit attached to my tongue piercing, trying desparately to control my gag reflex because the bit port is being shoved down my throat, no peripheral vision thanks to the blinders on my bridle, a giant butt plug distending my ass while delivering mind numbing electric shocks inside my rectum, tottering in hoof boots with no heels, and humiliated with bells attached to nipple clamps, I actually get turned on.
Well, I'd better be horny because I wouldn't last 10 seconds in my tack if I wasn't. And the great thing about being tacked up and restrained is that I can't do anything about my arousal. Thus, it's a positive feedback loop: the longer I'm in pony role, the more aroused I become, and the more I aroused I become, the longer I want to stay in pony role. While this is true, I actually do enjoy being a pony even after my "needs" are addressed, but the point is that for me ponyplay is intensely sexual. Few things turn me on as much as ponyplay.
As such, I really do admire those into equine role-play because I would be screaming my safeword in pony bondage if I wasn't aroused (ok, this is a little bit of an exaggeration, but seriously, being fully tacked up and not being aroused must be incredibly uncomfortable...and, without being turned on, this is not the good type of uncomfortable).
So clearly ponyplay is sexual for me, but for many people ponyplay is not sexual at all. This leads me to wonder if maybe I'm missing out on another aspect of ponyplay. One of my trainer's favorite ways to punish me (I mean actually punish me, not "punishment" during "bad pony" time) is to get me off a couple or three times then, leaving me in full tack, really start the training session. Interestingly though, I've found those occasions in which she has done this to be my most memorable ponyplay experiences (in a good way), and they have probably been my most productive learning experiences.
Ponyplay will always be sexual for me, there is no getting around that, but there is something to be said for getting lost in an equine role-play mindset.