Even with full USB OTG support a separate adapter would be required to connect USB devices with standard-A type plugs. This makes USB OTG largely useless for use cases like quickly needing to copy a file from a friend's hard drive or USB stick, unless you're always willing to carry an adapter with you.
I agree that there are some valid use cases for host mode and it surely would be nice to have for hacking, but I don't see the lack of it as a deal-breaker in this type of device.