The hinged lid is a modification of the enclosure that was later added. It is very comfortable, therefore I recommend it. There is an instruction manual. You have to print some parts (like the big handle and the hinges) and you reverse the top metal plate. Afterwards you can access the printer in the enclosure not only through the doors, but through the top as well. For some action this really is helpful.
But beware, there is an other pitfall waiting for you. Do have the advanced filtration system? Very advisable. If you do, pay attention: You have to print different hinges that can cope with the modified screws for the big vent. And those were added even later, which confused us... But now it is all sorted out.
But you are right, I second the demand that Prusa integrates all these things under one topic, the enclosure.
And there is yet another obstacle coming up: The next upgrade, to the XY Core printer has it's own enclosure, which actually is smaller... And so far I havent's seen a word from Prusa what owners of the original enclosure could do that do not want to throw that away...