I believe the reason Bungie wants to downplay the warlock as a healer is because you really can't be much of a healer with only potentially two healin skills (super/grenade) and quick kill times with free respawns. IMHO in this situation buffing teammates becomes more important as a sort of protection/buff class. What I mean by this is instead of actively healing your teammates you'll be doing DPS and landing supers that protect your teammates in important situations. Ie it seems that radiance is a team buff that might decrease damage taken by the team, but it was also mentioned it might be an area of effect Rez that could be important to prevent wipes. Also it is my opinion that in the devils lair game vid when the warlock respawns the Titan the Titan has a fully charged super either due to a passive ability of the warlock or a unique item (warlock arm band?). This would combine to make warlocks a very important support class that has the ability to prevent overall party wipe with crucial damage mitigation and group/buffed rezzes. I know if I'm anywhere close to what the warlock actually will be then that's what I'll be playing.