From your post, The Comanche has a very limited role it can play - since it's near worthless for extraction, rescue, troop movement or other typical helicopter duties where runways aren't around. It's purely a recon-combatant and information gatherer.

That can be said about almost all attack helicopters with the exception of the Mi-24 Hind. The AH-1 Cobra and AH-64 (along with virtually all other attack helicopters) only carry two people so they would be useless for directly performing the rescue, insertion, or extraction missions. However, attack helicopters fly escort for transport helicopters to lay down suppressing fire, greatly increasing the probability of success. Your statement is akin to saying a fighter has only limited usefulness because it can't fire cruise missiles like a bomber or carry cargo like a transport.

The RAH-66 Commanche is designed for recon and light attack. In the recon mission, its stealth means it's better able to sneak around in enemy territory without being detected. It can then datalink its findings to other attack assets like helicopters or A-10s or F-16s. That's a very useful capability. If you know where the enemy is and he doesn't know where you are, you have a huge advantage.