What Chroma said. Kommandos are just quite limited in the core Ork list. They just don't add much ability to a Warband.
They can potentially use their coherency distance to spread out a lot more, but since Warbands are big, that's not really a need. Besides, a boy and grot can add a big chunk of that distance as well.
They can potentially garrison some larger formations using the 50% Scout rule, but you have to add so many of them that it's cost-prohibitive. And, again, Orks have some pretty darn good garrison options as it is - Gunzmobz with Oddboyz, Warbands with Stompas and so on - so they aren't needed in that role.
In my
Blood Axe list, you can take a dedicated Kommando formation. That allows them to be used as an actual scout formation instead of being leashed to Da Boyz. Also, the Kommando formation in that list can take transport, so you can garrison with 30+cm move transports and assault across the board on turn 1. That gives them a couple of solid uses.