This is quite amazing for the long term viability of Steam Decks. Valve surely has mods and experimentation in mind but I look at this as a "goldmine" for long term support. Having owned portable gaming systems in the past, the plastic body and bezels are usually the first things to get scuffed and damaged. Even if I never personally printed a plastic Deck body myself to replace one that had started chipping, it probably increases the quality of 3rd party plastic bodys/bezels for the Steam Deck as well so I could buy one online(even after Valve inevitably stops making them one day) and have little to worry about. Having also bought all sorts of plastic 3rd party parts which were not originally modeled,(And I don't even mean gaming gear here. Car parts and all sorts of things can be named here) I've seen my fair share of things that snap in weirdly and have a little overlap and other weird quirks.
I wish more gaming companies did things like this over the past decades. It seems like just a few months ago Sony was raking some company over the coals for making panels for their PS5 consoles. I'm sure this will lead more quickly to 3rd party bezel makers for Steam Decks, since these look to be literal blueprints.
Comparing Valve here, to Sony, it's just shameful. So shameful.