For me, game collecting has nothing to do with the monetary worth of the collection, but more about preserving my own memory of a time that, quite frankly, was magical. I owned an Atari 2600 at 'launch' (a term that hadn't even been coined yet). I was 5. I ended up with 72 games and countless accessories before I sold it all in a yard sale 7 years later. A buddy of mine had an NES, ColecoVision w/the ADAM addon, so I have some nostalgia for the NES, the ADAM, and so on...
When I look at my 2600 collection, it immediately takes me back to when I just started grade school, as a kid, before girls, homework, a job, before I got married, before I had a kid, before responsibilities. I've bought plastic display boxes for most of the 2600 games I've bought (I didn't buy enough cases), printed all of the box art (some I've designed from scratch), created manuals from scratch for a couple of them (well, scratch, from an online text file that I added pictures, page numbers, etc.). A couple of cartridge labels were either destroyed, missing, or too damaged for me to enjoy the cartridge, so I made my own labels, from scratch, with a tiny icon printed on the label just to let me know that I made it. I'm proud of the work I've done on my collection.
The point is, I have no 'diminished opinion' of my collection from me making some display cases, labels, or manuals for my own collection that I never intend to sell anyways. I've never done it, but I wouldn't be opposed to buying a cheap repro, if it was a game I don't have for one of these early systems, and the seller was up front about it being a repro. I am also NOT cool with people trying to pass off repros for originals. That's why I add a tiny icon to the labels I make. I do collect for ME though, AND, I like showing off my collection, because I'm proud of what I've created. It also reinforces the memory of that magical time in my childhood.