I noticed that too...and that f/4 aperture diminishes one of the big complaints about cropped sensor cameras--inability to get really shallow depth of field.
Though it is roughly true that f/4 in 36x24mm matches only about f/2.8 in Sony/Nikon 24x16mm "APS-C" format for DOF wide open and light-gathering speed (and hence low light performance), f/4 in a larger format has some potential advantages over a "DOF and light gathering speed equivalent" lens in a smaller format: the higher minimum f-stop leads to easier optical designs, allowing wider zoom ranges and/or better optical quality wide open. But the initial FE lenses squander the zoom range potential, with zoom ranges no wider than for traditional f/2.8 designs! where is the 24-100/4 or 24-120/4, akin to designs already offered by Nikon and Olympus? Sony seems to have the goal of "smaller lenses to match smaller bodies" here more than with NEX lenses, which seems back-to-front.
In particular, the 28-70/3.5-5.6 kit lens for the A7, costing only $300 when bought in a kit, seems like a marketing stunt, designed to hit a marketing goal for low kit weight and price (US$2000).
Also, in the real world of high quality photography, away from forum spec sheet format wars, I suspect that the greater attraction of a larger format is the IQ benefits of greater dynamic range and/or image detail, rather than maximally blurry backgrounds. (For example, MF and LF photography have never pushed much in the direction of offering shallower DOF than 35mm film format; instead mostly offering lenses of distinctly higher minimum f-stops.)
If so then just note that the APS-C crop will be 16MP as it's a 1.5 squared change (area not linear)
Yes if the crop is all the way down to the 24x16mm of Sony's "APS-C" format, that gives 16MP crop from the 36MP sensor and about 11MP from the 24MP option.
But one question I would like answered is how much one can go beyond 24x16mm before vignetting sets in with various lenses at various focal lengths. My guess is that towards the long end of zoom lenses, and with any lens at a focal focal lengths beyond about 80mm, there will not be much of a problem. for one thing, the image circle of a zoom lens often increases in size as one zooms in, so that for example the Nikon 12-24DX cover the full 36x24mm frame near its long end, from about 19mm up.
One other feature not mentioned by Michael (or did I miss it?): these E-mpount 36x24mm format bodies are almost "universal receptors" for 35mm format SLR lenses, at least for fully manual and mechanical operation of focus and aperture. (Rangefinder lenses might have problems, due to highly off-perpendicular incidence of light near the corners with some such lenses.)