Why? They're one of the easiest sources of a good chunk of xp, tomes, and are often on wondrous tails too and for mog events are very generous. They're the most 'turn off your brain and chill' thing in the game.
Without cutscenes they clearly wouldn't be so rewarding, and that'd cause new players to miss out on some of the most iconic storyline in ARR.
I genuinely don't understand why anyone complains about this still. There's so many ways to get your xp/tomes that you could choose to never do MSQ again and be perfectly fine- so why not just not do it?