The lack of a viewfinder isn't a positive, personally.
They now have 3 models to choose from, no VF at all in X-M1, only electronic in X-E1, or both electronic and optical in X-Pro1. So what is there to complain about?
I have the X-Pro1 and X100s as spare, ditched X-E1 recently as I find the EVF uncomfortable to use (time lag). X-M1 should have the same IQ as the more expensive models, as the sensor is the same. Good way to enter the system, or cheaper spare body for those who need one. For landscape it would be fine, with the tilting screen and all.
The lack of a viewfinder isn't a positive, personally.That lack is striking in this case, since the X series has a strong association with innovations in eye-level viewfinders.
I'm not disputing that the manufacturers are free to do what they want with their design. And similarly we are free to decide whether a particular camera fits our individual wants/needs.
As far as the 'why' of no viewfinder, I think one reason may well be that there is a large audience who got into photography in the digital era with small P&S cameras that only allowed for composing on the rear LCD. There's also a huge audience that use cell phones as their primary camera and have to compose on the phone screen. Camera makers are always trying to attract new customers so forgoing the viewfinder makes for a very comfortable transition to those audiences. Further, the spate of new, advanced, fixed lens cameras makes for a wonderful transition to the cell phone audience as well who are used to composing with a fixed focal length; albeit one that's a bit wider than many of these fixed lens models.
It IS possible to use a camera without a VF. I even know someone owning an OM-D and switching to the E-P5 because he seldom uses the VF and prefers the rear screen (only in strong light for instance he uses the VF). Some of his pics below.
Tiltable tactile screens are no toys, they are really usable to take pictures. We just need to be open minded and wonder why we need the VF, because we really need it or because we are used to it?. Even if we prefer the VF (I do), not having one is a real option.