Haste doesn’t give an extra Action it gives a very limited set of actions. Dash, Hide, a single Attack, Disengage or Utilize. For a barbarian, fighter or rogue this would be amazing but for a monk it is likely to be useful but not outside the pale. Monks can already do several of these things with their own abilities.
Utilize can be very effective once you consider magic items.
Finally speed is useful but a 9th level monk is already faster than any other character. Being three times as fast instead of just double doesn’t meaningfully make a difference, unless the player is cheesing that in some other way.
With Disengage and Dash as a free bonus action and Haste action the speed can make a Monk immune to melee attacks and sometimes immune to all attacks because they can get out of range. That 180 ft move a turn. With a focus step of the Wind and haste Dash it is 270 foot. 270 move will take you out of range of almost everything. That is at 9th level.