To be fair, Esperanto is, as far as I can tell, not very widely used. The letter ĝ mostly returns Esperanto results. Using that letter in a place where others may need to communicate or type the letter would be a severe burden on almost anyone else you interact with, outside of Esperanto communities.

I'm sure there are plenty of people who share your frustration with accented letters, ñ, umlauts, etc, though. I'd hope that most systems can handle those letters, although I wouldn't hold out hope that Ĝ/ĝ would be high on the priority list.