Unfortunately most of those probably aren't dumped, and the majority of the Chinese gambling games (especially ones from IGS) run with MCUs as their main CPU meaning dumping them will be hideously expensive, if even possible at all..
The couple of thousand sets added recently are 99% UK machines.
Maybe you were joking, but yes, it's important they get emulated, they represent the various parts of the industry just like any other, and quite often the arcade gaming branches of the likes of IGS, Konami etc. are actually subsidised by their gamblers so they're kinda important.
One thing I've noticed from working on the ones we have is a lot of people have no recollection of some of the machines we have roms for at all, yet they must have all had cabinet designs, artwork etc. which may well have already been lost to time.
As games they're mostly ---steaming pile of meadow muffin---, yes, but so is 99% of the NES library ;-)