Switching gear

A reader sent me an interesting idea to solve the problem of tanks and healers being unpopular because hard to solo: What if there was gear which had different stats depending on whether you are alone or grouped? That way you could for example equip a tank with gear that helps tanking in a group, but increases his damage output when he is questing alone. Or healing gear that has more spell damage and less healing bonus whenever the healer isn't grouped. What do you think?