Well, I can’t speak for others, but for me: I was away from the game five months ago and now coming back and found this new tileset, I try it and it feels great. Not only feels great, it looks great, it also has a more advanced layer system for clothes and other equipment, some textures has double size (some special monsters) and the overall sprite quality is very good, sharp images, good contrasts of colors…
I was playing with the ChestHole32Tileset around half a year ago (it is good don’t take me wrong), but after playing many games, for me MshockXotto+ and MSX-DeadPeople fits much better ingame and also feels much better. ChestHole32Tileset uses somekind of RPG-Maker sprites with huge heads, chibi-like and looks very childish, some item sprites has very bright colours too and all of the monsters/npcs/player sprites are always centered looking at you with those HUGE heads of the size of a melon. MshockXotto+ and MSX-DeadPeople has angled oblique sprites which fits great in the game background and proper scaled heads in relation with the body size, this also makes the objects equipped in your hand and clothes look much better in general and the mosters sprites are great too. But as you know, tilesets are all about personal tastes, this is all about how you like to play CDDA and how you like it to look for your own tastes.
As you say, it becomes popular very fast, lot of CDDA content creators in YouTube and Twitch use it too for a reason.