The hi hat is tricky. It can be obnoxiously loud and also overly subtle. Compressing is an option but you lose dynamics.
Yeah... to me, how the hi-hat sits in the mix is one of those things that really differentiates between an "OK" mix and one that's truly a cut above. I also understand it can be a hard piece for the FOH engineer to get a handle on because a lot of drummers don't seem to have very good technique on that piece of their kit. Which may be why it's not mic'd in the first place.