If all hands are imported, players will still be able to analyze their own game, check played hands, EV, winrate, redline, 3bet %, blind play and etc. If you stop importing all cash hands, this will be the same as no HUD and no Hand History for cash games.
I think that would be the better decision instead of stopping importing cash HHs at all.
Also if you start support HUD for alias (which is requested 4 years ago here -> merge hud stats of two players on two different sites? ), people who had older alias for the opponents (or accumulate nicknames over time) can add them and use HUD during play or when analyzing opponents.