The database actually already has a field for specifying the image. But that's as far is it has gone.
It is a big job. Where does the image get displayed? In the list of players on the Database tab? In the list of players on the Players tab? In the list of players on the Stats tab? And the Tables tab? What about all of the dialogs used to buy-in, bust-out, add-on, rebuy (don't forget undoing those actions)? And how about the tournament history? And rankings adjustments? And chops? And player movement suggestion dialog? And what about the layout? The Player Rankings screen? Seating Chart screen? Player Movement screen? Existing layout tokens, like <rankings> or <prizes>? And don't forget messages displayed for Events.
And that's just off the top of my head.
I honestly would like to implement this, it's just a matter of finding the time versus priorities.