Let me be really clear about one thing. I love the mirrorless cameras for the EVFs and all the power and convenience that gives you when shooting but I have often railed against the trend to grow cameras smaller. I'm so happy to see a bit of a move in the other directions. Both Panasonic and Leica have come out with cameras that have more "real estate." More places to put your hands and more places to put full sized, vital plugs. More interior space to wick away heat from sensors and circuit boards. More of everything.
The whole camera size preference cuts across two intersecting cohorts. On one hand we have professionals and on the other enthusiasts (everyone else is shooting with their cellphone now). As the pros age up they'd love to have lighter and lighter cameras and lenses because it's a shoulder and lower back saver. The smaller weight is also an energy conserver. But even the most physically feeble pros still need certain camera parameters in order to do their jobs correctly. They need to be able to have access to controls, to be able to hold the cameras correctly and to use them with flashes, remotes, plugged in video monitors and also tethered to their computers. As one reader pointed out, when buying a shrunken camera, like the Sony A7 series, you get a nice camera and a bag full of compromises. The A7s do nice video but.... the batteries run down quickly (too small), mini and micro HDMI cables break and get loose at a much higher rate than the full sized HDMI cables (more contact area more torque distribution, etc.), there's insufficient internal space to maximize heat management and, since the cameras have full frame sensors there is absolutely no weight or size savings when it comes to nice, elegant, fast-glass. FF lenses are just always going to be heavier.
So, you get a mini-camera that's horribly hobbled for pro shooting. I'm sure this is what Leica was considering when they designed the SL. I think it's a sleeper video camera that will break out and be the next step fun the hybridization process between pro stills and videos. Why? Because there's enough room to hang stuff on the camera. And I think most users have issues with the size of the smaller cameras where handling is involved. Too much finger, too little camera.
Most of the same arguments can be made for the GX8 from Panasonic. The body is bigger and it is more comfortable to hold and use. I'll also bet that it handles heat distribution from video more efficiently than older body designs. If it were all about handling I'd be smiling more about the GX8 but I'm still pissed that they went back to a weird size for the microphone inputs and capriciously elected to not include a headphone jack.
I notice that the cameras the a lot of serious photographers still use are not shrinking in size. The D810 is an ample package, as are the D4s and the Canon 1DX. The Canon 5D line is still a full size camera body style. And the Nikon D750, while measuring smaller still feels like a full grown camera.
I love the Olympus EM-5.2 but I'd love it even more if was bigger. That's because I love the features. The stuff like killer IBIS, a great EVF and a nice movie mode. But I'd love it even more if it was integrated into a body that had batteries that lasted through whole video interview or half a day shooting stills. And if I'm carrying only one camera and a nice lens I don't really care about the weight. I'd rather have the excellent handling. A nice, good fitting outline to wrap my hands around...
But there is another whole cohort out there that loves the idea of "small" and drives some parts of the market. These are the users whose overriding priority for a camera are whether it fits in the pockets of their tight pants. I guess this group is why Sony is making a killing on the RX100IV. I think the RX100IV and its ilk are transition cameras. They are cameras for people (who own only one camera and..) who thought at one time that they might want to be real photographers but who have decided it's too much work so they are downscaling from DSLRs to high end compacts on their inevitable transition to being a phone photographer.
Most styles and designs are like swinging pendulums that overshoot the mark of balance and swing into silly and excessive self-parody. Cameras are no different a fashion statement. The phone is one extreme while the medium format cameras and ultra pro 35mm style bodies like the D4s and 1Dx are the other extreme. Leica is wisely returning to the middle ground. To stasis and to the normal order of things where the tools fit the hand as well as the imaging purpose.
A couple of analogies about size: While manufacturers could make framing hammers much smaller and lighter the skinny handles wouldn't fit in beefy hands well, would not provide a secure grip; and a smaller, lighter hammer head wouldn't drive a 16 penny nail worth a damn....
I'm okay with smaller sensors. That's cost savings and depth of field on the opposite end of the spectrum from full frame dof control. I love eves over optical finders. But I never thought I needed to trade those attributes for body size. Like most pampered North Americans, I want it all just exactly the way I want it. Until I change my mind. Again.
I prefer bigger cameras, up to a point. In fact, I hope the makers of cameras don't overreact to the swinging pendulums of camera fashion and start making giant cameras. But they might be able to sell them for higher dollars. We like big packages and still believe that bigger is better. I saw that this weekend at the Formula One races in Austin. The parking lots were filled with big Suburban SUVs and pick-up trucks. Big cars for big people. hmmmm. Any camera makers paying attention?
Besides Leica and Panasonic I mean....