Lowbie looters encourage gear circulation, especially for players who can never get said gear on their own.

Being looted, encourages progressive game knowledge, and will better you in the long run as you learn to
equip a lethal set in minutes.

Full looting creates a longer IC timeframe of crippling characters.

Being full looted gives greater encouragement to put thought into your fights, pick your fights, and learn to win.

Full looting (the really nice sets) enables players to bring down the uber-successful player a notch and make him killable without grouping up against him.

Being full looted slows down the murder-everyone mentality, because god knows when my characters are nicely dressed and I am playing a high-aggression character, the better eq I get, the bigger the murder spree.