As a warlock, I sometimes offer myself up to healers when I see a bunch at the training dummies. I run in and out of ground heals and spam Life Tap, since I can't kill myself with the spell anymore (it fizzles).
Actually, I think Rejuvenation is different from Healing Touch. Healing Touch is a direct heal -- you cast it and then you get healed. No cast, no Touch. Rejuv, on the other hand, a warlock can set and forget, much like a Lightwell click. I already love the Lightwells to click prior to Life Tapping, even timing that mini-HoT so the tick hits me right after I Tap.
Also, with the burning resource that destruction warlocks have, Cauterize Master off the Fel Imp was insanely useful, being off the GCD and a HoT, letting the warlock do something else in the place of Ember Tap (which heals, but costs an ember, and takes a GCD). Rejuv might still be on our GCD, but it would heal the warlock while she's doing other things.
Healing Touch on the other hand, that's you are casting that OR you are DPSing, not both. It's perhaps a slight difference to everyone else -- one GCD versus an entire cast -- but I think it makes a palpable difference to the warlock.