Drop rates are fine. If you don't have the time and/or patience to clear it 99 times, then that's your own fault, sorry. :') Everyone knows that's what this game is really about nowadays - mindless grinding.
...
Like seriously, who even thinks like that? It's pathetic.
Consider the following:
1. You can't use mounts in 99% of the cities, which is where most people hang out.
2. Sure, you can use mounts in the housing areas, but those are empty most of the time, save for a couple of FC members you might have around.
3. There are a bunch of cooler mounts you can get which require no grinding/farming. The gobwalker from A4S is an example (100% drop rate).
4. Regardless of how cool you think a mount is and how hard you work to get it, chances are you'll end up getting bored of it sooner or later.
Not to mention the Mogstation mounts. I feel bad for people who wasted literally a couple of days of their lives farming for all the birds to get the Phoenix mount, and then spend 24 bucks on a Carbuncle. Really makes me wonder...
Basically, what I'm trying to say is, don't buy into this game's utter garbage mount system. Not only do they make it unnecessarily hard to get some of the mounts, but they're barely worth it considering you only ever use them in the open world (which is empty, let's be honest).