As esongbird24601 stated, the custom template system is intimidating, while I understand it's hard and time consuming to implement a fully modular system, anything that makes the current system more user friendly for the "layman" would be nice.
Though I'm afraid, that this is way too complicated to implement, it would certainly sound helpful.
I upgraded to grandmaster for the custom templates and have never been able to use them because the process feels overwhelming and intimidating. I fully support anything that makes this feature more user friendly, especially on the input side of things!
I'd be interested in custom article templates being able to adjust the look of the input side of things. This would be pretty nifty if you, for instance, have changed the name of a section in the custom template for the output, because then you could have the section name match on the input side. Though I will say that I'm almost positive this has been discussed at various points in the past (like when custom article templates were first released), but I couldn't tell you off the top of my head what verdict was reached back then.