It's disappointing more games haven't been added like other Samurai Shodown games, King of Fighters, World Heroes, etc....

I don't know they would quantify "poorly" but I'd guess most of them had better than average sales. The Metal Slugs were the most popular.

Seconded. I already have all of the SNK classics and would buy others if they showed up here.

I'd buy 'em all of the rest, if they showed up here, as long as they were not censored like Art of Fighting II and Baseball Stars II. Except for Galaxy Editions of the King of Fighters games, I think we're stuck with the same ones that Humble got. There were a lot of others available at the Microsoft store. Not sure if they're still for sale there but be prepared to spend a few hundred dollars for all of them if they are.

I dunno if they did sell poorly on gog, but I love these neo-geo games. Note though, that it's hard to get any co-op or versus match going on gog. It was literally easier to practice and get a 1cc Metal slug1 run on normal, than to find a co-op partner willing to play a bit co-op here. No joke... Neo turf masters was delisted at some point too and it seems like a permanent -1, which is a shame and I doubt we will see any additions.

Switch has a good selection of these games, through their ACA neogeo series. They are pretty barebones emulations, but they run well considering it's on switch, where every emulator has like +2 frames of input lag vs pc.

Steam has a rather small selection, though they have some games which are not here on gog, e.g. kof97gm, Samsho collection (1-5, 5 special, 5 perfect) by Digital eclipse that has their other games here on gog, so dunno what the holdup is here.