Helldritch
Hero
Truly you do not understand the Monk.
Hit and run is the Monk.
Extra speed? It's so you can get back out having crossed the distance to engage in melee.
D8 hit dice? It's because they're supposed to avoid being hit.
Most Martial Arts features not working in armour or with a shield? You're not supposed to tank as a Monk.
Mobile might give you a lot of features you can already access, but all of them either stack, or are outright free compared to without the feat.
Most of this is true. But the monk is not solely for hit and run. Patient defense is there. Especialy if the monk is hasted as I have suffered a player do in my games. 1Ki on flurry, 1 Ki on patient defense. 5 attacks, and I was attacking him with disadvantage. With a +1 ring of protection the little guy had AC 19 at level 12. Not an easy character to hit. He could keep that up for 6 rounds if needed be (less if he used Ki for something else).