That's the thing, if you compare it to the other simic level 1 abilities, the intention is that they each be occasionally situationally useful.
However, unlike the other 1st level simic abilities it's quite easy to build a character who the answer to "how often is it useful?" is "most of the time". All you need is a class ability that allows you to propel yourself vertically upwards. And there are many of those: Fly spell, druidic shape changing (after level 8, change into a bird, fly up, revert to natural form, glide), Spider Climb spell, Fey Step, Storm Sorcerer ability, Misty Escape (Warlock), Tiger Totem, Eagle Totem barbarian abilities, and I'm sure there are more I haven't thought of.
As for "why" you would want to use it, the important thing is not the maximum speed, but the fact that it is "free" movement, in addition to what you can normally get from your move and dash actions. So you could use it to:
1) move between melee targets that would otherwise be too far apart
2) close rapidly on an archer
3) Stay well out of melee range, even against superfast enemies
4) surprise a target by beginning a round well beyond their visible range