Do it!
when playing the physical game (usually just myself and ex-roommate, but sometimes with my fiancee and his) I usually take a character that fills out the party. If they take spell casters and tanks, I pick a thief. If he plays utility I pick a fighter type. Some balance would be necessary for 'random' parties. Harsk, Valeros and Amiri might kick major butt, but Barriers and checks that require Intelligence and Wisdom will throw a wrench in the works fairly often. Same with a party of Ezran, Seoni, Lini and Lem; they will inevitably need some muscle.