My mission is to make the MiSTer experience the best it can be. The purpose of the Arcade DAT is to verify you have the proper files inside your MAME and HBMAME zips. If you are downloading the MAME/HBMAME zips through Update All then there's no need to verify them because those are sourced from proper MAME/HBMAME sets. The Arcade DAT does include files that are not retrieved through Update All. These include the Darksoft Neo Geo Romset that go into the MAME folder and Battletoads that has its own separate folder. If it's helpful I can make a folder called mame darksoft so you know what is Darksoft versus MAME.
I will always include for download MRAs, RBFs, MGLs, and other needed files besides games in each of my updates. These are sourced through Update All and verified to work. The Battletoads core will need to be added manually with its RBF and MGL file. Also add in NeoGeo-MVS_20220218.rbf so your Darksoft Neo Geo games work and play. All the available MRAs for Darksoft Neo Geo are sourced here, https://github.com/blackwine/NeoGeo_MiS ... r/releases. You can remove The Eye of Typhoon - Tsunami Edition from alternatives because a Darksoft version of the game does not exist.
Neo Geo Pocket and Neo Geo Pocket Color are in the Arcade DAT because Jotego designed it as an Arcade core called jtngp.rbf. I agree that Neo Geo Pocket and Neo Geo Pocket Color are handheld consoles and should be in the Console core folder but until that change happens if it ever does, they will remain in the Arcade folder. The Arcade DAT makes it easy to locate the NGP and NGPC MRAs. Instead of having to dig through files and folders, the NGP and NGPC MRAs are displayed immediately upon clicking on the Arcade folder.
The Arcade DAT focuses on changes that Update All provides. The Console DAT mostly focuses on the changes No-Intro frequently makes. I have less focus on supplementary items but I want to include them for those wanting to explore what each core has to offer, (example the massive library of NSF and SPC music available in the NES and SNES cores).