Your suggestion is good and I would support this too. But this can't happen in the short term.
Both tool were developed as stand-alone tool and we provided the adapters to make them usable in SNAP. This should have ease the usage even though there are problems to be solved. Beside the legal issues, they are solvable, cause at the end it is all ESA, there are also technically issues. Both tools, Sen2Cor and Sen2Three, need to be changed to work within SNAP. Probably also some changes to SNAP need to be done. All this need to be coordinated and some one (ESA?) needs to pay for it.
So, you see, it is not for the short term. But maybe we can start to push the right buttons.
Anyway, thanks for sharing your suggestion.