Its a fair idea, however, that would ultimately run into the same issue of the target being unable to get the full benefit from it. Even if you go with the heal, you can only heal them to their HP cap. That, on most ATs, near/at full build, will leave them capped and the power demanding only recharge base (using the Defender stat boost example, since, on a Stalker, the biggest benefit would be to a set without a +Max HP power - they'd cap out at their little over 2k HP).
(I used Stalker as an example, since, as far as I know, they have the largest difference between their default Max HP and their cap Max HP.)
Meanwhile, if you went with +Absorb, if you cast it on the same character, they would effectively be given an instant boost to their HP equal to the total value of the absorb. This means that on squishier ATs that can actually use the bonus, it'd have a true effect on them. Meanwhile, on the already beefy ATs, it'd be like offering them a bulletproof vest to block the first major shot (or a horde of smaller hits).