I'm not using Unity, so I won't talk to that point, only the phone/tablet opportunity you think they should be ignoring.

Apple is already a heavyweight in this area and Google/Samsung have a dominant second place. Viable tablet alternatives need to establish a foothold now, before there is too much lock in from the existing entrants. Every iOS or Play app that I buy will make me (as a consumer) less likely to switch platforms. This is true for me, even as an early adopter. For a normal consumer that doesn't have the free cash, nor the desire for constant change, it is a killer.

Every month that they fail to have this out the door, they lose potential customers.

[edit: just a bit of editing]