I've mentioned this before, I know, but the Counselor character was originally envisioned as more of a political officer, there to advise on adherence to Starfleet and Federation Council policy - which is why she had a position on the bridge. But they decided that was a little too Der Kommissar
, and altered the role. Which worked out well enough, obviously - the show is beloved by millions - but I do wish they had put a little more thought into developing the character's *new* role. Nothing dramatically different from what we got, but maybe some of Troi's insights could have come more from her expert skill and intense study of psychology and xenopsychology, and a little less from a special power she had by circumstance of birth? A somewhat more confident and competent Troi from the get-go, rather than having to wait until "Face of the Enemy" and then further for Jellico to make her wear a uniform for that Troi to show up.
Edit to address the actual OP question (forehead - smack): Part of my point was going to be that given the original nature of the role, yes, I believe every ship above a certain size/power would have such an officer.

Edit to address the actual OP question (forehead - smack): Part of my point was going to be that given the original nature of the role, yes, I believe every ship above a certain size/power would have such an officer.