That still doesn't address the entire issue.
All of the +regeneration powers should be affected because +healing is the correct enhancement that affects them and heal sets are what they accept. That's an entire group of IO sets that will give one less set bonus (2 bonuses instead of 3 for a 4-slot IO set, etc. etc.) because the [Healing Bonus] stat is completely non-functional in the CORRECT application on a defense powerset of a tanking archetype. This is a game-balance bug.
ALSO, since +healing is also +absorb (IE: temporary health), the max hps from Dull Pain could be reasonably expected to increase as well from the +To All Healing set bonus.
While it seems like you know the game workings a bit, dismissing it as 'not surprising' without acknowledging it as balance problem seems to imply a lack of appreciation for the impact this has on other players. I accept and appreciate the explanation of why reconstruct might not be accepting outside modifications, but being one of two heals in the regen set, it's not benefiting from +To All Healing IS a valid issue. I assumed it was all a bug; perhaps you're relegating SOME of it to just a significant flaw, but that leaves all of the regeneration aspect and so I am hoping a dev will look at the entirety of it.
I have a significant amount of hours of my life invested to aquire the 4-piece set bonus 5 times over (unwise perhaps, but this is the way I went about it) only to reach level 27 on the appropriate character and feel horribly let-down by the 30% [Healing Bonus] doing absolutely NOTHING.
As for why [Healing Received Bonus] doesn't affect self-only powers being that it's the standard for self only heal powers, I first have to ask 'why is that the standard'? A powerset whose entire shtick is self healing might logically suffer less (or more depending on ones conceptualization of the thing) from [Healing Received Bonus] debuffs; But by what logic does 'average Joe corrupter' deserve complete immunity to [Healing Received Bonus] debuffs of the Hami raid for their self-only heals when the flip side of that coin is that WP/Regen don't get the benefit of [Healing Received Bonus] for the entirety of the rest of the game's content?
The issue of how people cope with [Healing Received Bonus] debuffs can be solved in a way that doesn't so negatively affect another aspect of the game. I'm sure of it. Even if that means tuning or reducing the number of them present.
That said, if an enemy debuffs the ability of your body to be healed then it should affect even self-heals. Are [Healing Received Bonus] debuff attacks really that common? Is there some logical, conceptual, or balance reason why self-heals should be immune to suffering from healing resistance? If a medusa turns me to stone I'm not too certain how my white blood cells are gonna get where they need to be or how I'm gonna press the button on my tri-corder... (sure that's a hold but I'd expect a 100% [Healing Received Bonus] debuff along with it. And let's not forget, [Regeneration Resistance] is already an existing 'Debuff Resistance' combat attribute. Let people have more access to it if that's what's needed for Hami. Green inspirations giving [Regeneration Resistance] for a minute perhaps?