Monk is somewhat weird, but it is one of the least liked class overall since like, HW or so. In ARR they were "somewhat" popular, but that was more virtue of only having monk and dragoon as melee DPS and dragoon was some big fuckery with the super long jump animation locks. Then Ninja was added in 2.4 and that started the descent of Monk into the least played classes ranking. There was a small bump in 5.0, not because it was fun, but because it was super strong due to poor balancing(happens all the time on new expansion patch, expect some broken shit in 6.0 until 6.0.5 or 6.1 depending on the severity), and then everything else got buffed and monk fell back by 5.1.
That's why it got a full rework, first in 5.4(I think it was?) with the removal of GL stacks and some other changes which made it less annoying to play, but somewhat boring, and now with the 6.0 addition of a full layer of new mechanics to make it less boring.
Ultimately, if you like monk or not depends a bunch on what kind of player you are. It's pretty apm intensive, with positionals on every move(next expansion they're remove positionals on a couple of moves, but it'll still require more positionals than every other melees, so lots of moving around especially with the lower GCD) and before the 5.4 rework had a huge skill floor(dropping GL stacks was a disaster) while feeling like shit when soloing and doing 4man dungeons. The GL change in 5.4 made that a lot less shit though, so it's actually somewhat enjoyable currently imo, but pretty boring. The 6.0 changes should make it less boring with a more standard "ressource minigame" added to the rotation which should spice it up, and stuff like the new teleport should also make it feel great to dodge stuff and what not. On the flipside, since they're adding Reaper, I doubt Monk will see much of a popularity bump, competing against both the old favorite SAM and the new shiny edgy melee Reaper.