I kind of agree that everything should be under one roof for the sake of sanity when it comes to RecipeDef and ThingDef. Just put it all in ThingDef, since recipes are currently only ever used to make things and they always reference only one specific thing as a product. The only reason you'd want the two separated is if you need some order independence (which doesn't seem to be the case for anything currently in the game...?)
I mean, unless you want to separate concerns into ThingDef and CreateDef, where you'd unify Items and Buildings as just generic Things using only their ThingDef tags to differentiate them while the CreateDef would describe how you create, trade, and remove the thing during play. That makes the most sense to me.
Imagine a mod that enables a colonist to build some tribalwear on the ground with a welding torch and have another colonist swoop by to dance on it for a little joy, who can then pick up and wear it. Optionally, at a workbench a colonist can create a solar panel and wear it as a hat until you give them somewhere to place it down to actually function as a power plant. All with just xml! Pointless, but flexible!
NOPE, I forgot that deconstruction recipes exist and that's a very valid reason to keep them separated. Nevermind!
Imagine a mod that enables a colonist to build some tribalwear on the ground with a welding torch and have another colonist swoop by to dance on it for a little joy, who can then pick up and wear it. Optionally, at a workbench a colonist can create a solar panel and wear it as a hat until you give them somewhere to place it down to actually function as a power plant. All with just xml! Pointless, but flexible!
NOPE, I forgot that deconstruction recipes exist and that's a very valid reason to keep them separated. Nevermind!