The roughness is about on par with installers trying to compete on price. They don't take the extra time to scrape the flakes well or run a pole sander over the surface before applying the clear coat, and/or skimp a bit on the clear coat to save money on materials. The only way to fix an overly rough floor is to sand the entire surface thoroughly and then apply another clear coat.
Unfortunately, most customers who are not familiar with garage floor coatings don't know enough to ask what the surface texture will be like or to specify how they want it before agreeing to the job. Full color flake floors typically have a rougher texture, but they shouldn't snag towels either.
Full flake floors won't sqeegee like smooth concrete or a coating with minimal to no color flakes because of the texture. There will still be some water on the surface, but what's left evaporates fairly quickly in the right conditions.
I would try running a mop to see if you have issues. If you do, I recommend contacting your installer to discuss the problem.
