I mean, they used to do that, at least for 1st round picks who didn't sign. But I guess then it brings in the question of "players who chose not to sign" vs. "players you chose not to sign": of course there are also many players who pass through the 4 NCAA years and the team that drafted them doesn't even want to sign them anymore. So I definitely don't think you should get a draft pick in the latter case.
I guess it doesn't affect the player's rights or freedom of choice in any way if you did offer a compensatory pick as you describe... contingent say on at least having offered the player a max-value ELC as a bona fide offer. If you've met that minimum criteria of a registered bona fide offer that is as good as any team could offer them, then getting a compensatory pick a round later seems pretty fair to me. Most of these cases, the player has just developed so well out of a late pick already. Farrance was picked at the very end of the 3rd round, so getting a 4th rounder in compensation for a player who has panned out that well would still hurt. But at least it is something. If a player simply has other reasons for not wanting to sign, I guess that's fair.
So if we offer Farrance the max ELC of $925k with $92,500 signing bonus, and he still won't sign with us... especially since he can definitely step in today and start burning that off... then ok, getting a 4th round compensatory pick seems fair to me. Doesn't affect the player in any way.