For me the appeal of new 8-bit games is the same it always was, 30 years ago or today. Why, just becuase technology has made games much more sophisticated on new technology (and I enjoy the latest games on new tech too), should it make new games on old, less sophisticated systems of years passed any less enjoyable?
Why, just because they are new games on old tech should they be any less fun to play than new games were years ago when the the old tech was new? I still enjoy playing chess, and it's an ancient game. Is chess only fun to play now with 3D graphics on the latest PC? People still like board games, even though they rely on no technology at all. Baseball and Football have been around for 100-200 years, but they are even more popular today than ever! Old does not equal bad or boring!!!
We have tons of interactive media, but billions of people world-wide still enjoy non-interactive movies, new or classic, or even classic books (whether in books or on a Nook or other electronic tablet). are new books only good if read on technolgoy instead in a bound book? So why should it be any different than playing new games on old systems?
Personally I think it's all in people's heads. They have been brain-washed by the industry and media into thinking it's only good if it is on the latest technology. If more people would give old tech a chance, they too would realize it's still good too.
I see this mostly the same way. If it was good then, why shouldn't it still be good now? Now, that's a bit subjective, some things (disco) were abominations and thank Odin they're gone. But other things stand the test of time so why not still like them?
Much of my liking of 8-bit software is, honestly, because I grew up with it, it's what I got used to. Atari and Vectrex games meant the world to me back then and hold a special place with me to this day. I very much doubt that if were born today and never laid eyes on 8-bit software until I became an adult 20 years from now that I would be compelled to like any of it or seek it out or try to re-invent it or even understand why anyone would give a damn about it. It's how I feel about '50s-era pop music, it is horrible and I can't believe anyone could like that stuff and I wouldn't care if I never heard any of it again. But people who grew up with that music love it. Same goes for the 8-bit games.
Part of what I like about 8-bit games (not including 8-bit word processors and art programs and such because those are miserable failures compared to what's currently available) is the fact that since the graphics were, for the most part, laughably primitive and incapable of representing reality, the programmers had to concentrate on making the action playable and fun and interesting. Simple rules, simple goals. Asteroids and Star Castle can go on forever doing the same thing. Xevious takes a while to go through the entire land but it's just super Galaxian. But I'm a big twitch/shooter game fan so I'm biased. Sure, if you made Dig Dug today you could render everything practically photoreal and it might look like real dirt with real beings being blown up by real guys in vacc suits. So what, I never cared that Pole Position didn't look like a live-action race or that Tempest didn't represent anything real, I loved the gameplay and the difficulty levels. Defender supplies more than enough blocky 8-bit shapes to convince you that you're seeing a spaceship flying over ground rescuing humans and killing aliens, nothing would be gained by adding 64-bit graphics but everything would be lost if the action changed. Vector graphics are even worse, wire-frame shapes moving around other wire-frame shapes? But the gameplay of Battlezone and Star Trek is unmatched... if you like that kind of gameplay. If you're into RPGs or first-person perspective combat shooters with realistic texture maps and interactive lighting then all the 8-bit games suck.
Another part of what I like about them is due to nostalgia. I see those games, I see just the packaging, and I feel like a kid again. It applies to original Hot Wheels (before they ruined them), LEGO sets, WB and MGM cartoons, all of that stuff. One of the cool things about new homebrew games is that it allows me to feel that "oh boy, a new game came out" rush again, like when I first owned an Atari 2600 (and, later, an Atari 800) and went to the store to buy a game for it. Now I have a Vectrex and Atari 5200 as well so that's 4 separate ways to experience that feeling again when someone makes a new homebrew game. I mean, the Crash wasn't necessary, those systems could have survived longer than 1984 and some company could have released a "real" Warrior for the Vectrex or an official Warlords for the 5200, right? So we had to wait 20+ years, big deal. It is for that reason that I very very very much prefer homebrews released as physical carts with boxes and manuals, so it's exactly like when new games came out in stores back in the day. It also explains my love of the new Camaros, Challengers and Mustangs even if they're not as cool as the original '60s/'70s versions, the nostalgia pull still works because they finally got close enough to that ideal.
I think the OP would get a truer, unbiased answer if he were to ask the question only to 8-bit software fans who didn't grow up with 8-bit games and only got into them later in life so nostalgia and familiarity couldn't play into the answer.