JICYMI.

What a tragedy, is there any reason why these games get pulled?

I thought the games on GOG do stay forever unless there is the specific reason. What IS the specific reason?

Pity, would of liked to see stuff such as Sly Spy, Boogie Wings, Nitro Ball, Desert Assault and quite a few others that aren't bogged down by licensing issues.

Licensing maybe?

The console versions were all pulled abruptly last year around November, IIRC. I think they were branded under both Retro Classix and Johnny Turbo.

I wouldn't worry about these becoming unavailable long term but this may very well be last time they are on GOG.

These are all Data East games published by Ziggurat. Presumably, a license/contract expired between the two companies. They're also being removed from Steam.

Good thing I have them already. They shall be safe in my library.

Eh. Just because something's old doesn't mean I'm necessarily interested in a game. *shrug* Bought Super Burger Time and the first Joe & Mac a good while ago. I looked over the rest again yesterday, and only the Joe & Mac sequel may be worth a purchase. I don't particularly care for mediocre beat'em'ups/shmups.

This.

Gate of Doom and Wizard Fire are good games, quite surprising they are arcade style for what they are.

The games you have bought stay in your library no matter what.
But that doesn't mean that GOG's catalog is set in stone.

"Digital preservation"

According to the reviews on GOG and Steam these are not good emulated versions. The emulation is stuttering and there is an input lag. This is not really good for arcade games. I looked at the entries at https://www.gogdb.org/ and you can see there that they have used the Unity engine for the emulation of these arcade games. This probably explains the stuttering and input lag. The censorship in Night Slashers mentioned in a review gives also an indication that the used ROMs aren't good as well. In this state I won't be surprised if these versions haven't perfomed well on Steam and GOG. Considering the length of these games (about 30 min.) all of these games should have been sold as one bundle for at most 10 Euro or Dollar.

IMO that's shameful that Ziggurat is delisting these games, instead of doing the right thing, which would be to fix & uncensor them.

DerBesserwisser summed up a way to play these games with MAME 2003-Plus.

https://www.gog.com/forum/retro_classix_joe_mac_caveman_ninja/play_it_via_emulation/post1

Each of these games should have a .zip file in the StreamingAssets folder which can be used with MAME 2003-Plus as described in the linked post.