Positionals add an element of adaptation to the fight, where you need to adjust yourself based off which direction a boss is facing. It's the melee version of a Black Mage knowing when they can greed an extra cast out. And frankly, melee are pretty damn boring without the positional bonuses. The extra movement needed and knowing when and how to squeeze out another help make melee, especially monk, much faster to play.
Sadly, I do think they're going to go the way of the dodo next expansion. The problem is that I don't see anything to replace the positional system because, especially in the case of Monk, we have never received anything new to replace removed systems and abilities.
To compound on that, I think one of the reasons Monk is one of the lesser-played jobs despite being very strong is simply that it's just not fun. Monk is not more complex than the other melee. Making it simpler and more accessible won't get more people to play it, it'll drive people who do like playing it to go do something else.