I feel like knowledge of a desktop QWERTY keyboard has little affect on your mobile usages, aside from knowing which direction your thumb should move towards. Given the fact that (most?) people use only their thumbs when using their cellphone keyboards, I would argue that's reason enough to design a new keyboard based around this type of usage. Right now I think QWERTY is just a crutch for mobile keyboards until someone really makes something stellar.
I personally like message ease. It feels like a step in the right direction.
With a mobile keyboard, it is simple to allow multiple, easily-switchable layouts. So, although QWERTY probably won't go away soon on account of familiarity this is no reason not to introduce an alternative.
I vote yes. A majority of people have already invested a ton of time learning propper typing style on physical QWERTY keyboards. Translating that existing muscle memory to use a similar style on virtual keyboards is a lot easier than people would guess. After about 30 minutes of practice on a virtual keyboard people normally get their typing speeds to a slower, but adequate level in order to be productive.
An entirely new input system offers very little opportunity for re-use of existing skills.