I MUST OWN THEM ALL HRRRGRRBLLL DIGITAL HOARDING
Sorry about that. I tend to get a little foamy when I digitally hoard. Anyways, counter to your point it's fun (for me, YMMV of course) to have as many as you can get. Sometimes I'll fire up MAME and simply pick out old games at random. Some I remember, some I never have seen before. It's like being an archaeologist in your own past. I'll do the same thing with C64 archives and Amiga archives (look for Amiga Tosec). Scores of Atari 2600 games. All the video discs for Daphne (the videodisc game emulator). Dragon's Lair, anyone?
It's a wish come true for younger-me. I used to mow lawns just to save up and get an Atari cartridge. Now I can download Stella and inside of ten minutes have ALL of them. Fun! And yes, someday I will make a MAME cabinet. Oh yes. It will be glorious.
So basically TL;DR it's really fun to poke around with. And really, with the price of storage these days you can store the entire library of an entire genre on a few blu ray discs. A 3 Tb hard drive is about $100 at NewEgg. Why not have them?