I think they give out just the right number to keep us appropriately stingy about giving them out to employees. I know I have just 3, so my standards are pretty high. I've given out only one so far this year _ to an F/C FA who did not one, but two bev services on a JAX-ATL run with the seatbelt light on the whole time. 99.9 percent of FAs, IME, would take that as an opportunity to take a break and read a magazine.
I do agree that the program is disproportionally favored towards FAs. They're the ones we spend the most time with. I gave all three of mine last year to FAs, but if a CSR really blew me away with service, I'd probably figure out a way to give him/her the cert. Just doesn't tend to happen.