Good post Jorgen. Very difficult to express the difference between a great OVF and the best of today's EVF, but you did somewhat do it. Excellent point regarding the difference between SLR and DSLR OVFs.
I think it has to do with expectations and experiences being set by decades of using OVFs. I forced myself to get an A99 at a time when I had two perfectly serviceable A900s (neither of which I still own). Despite off-putting experiences with a NEX-5, I figured I had better get with the program, or I would have to swap DSLR systems again. However, IF Sony had issued a A900 replacement with a OVF, that is what I'd be shooting right now. I know I'm not alone in that distinction.
Unlike Guy, I do still see a gap between EVFs and OVFs, but assume that will diminish in short order as (1) I become more assimilated with one and forget the other over time, and (2) the EVFs improve in areas where they still lag OVF.
The ability to see what you will get with EVF is a profound difference. As game changing as the instant LCD feedback of DSLRs was IMO. Unfortunately, it comes with baggage attached that is off-putting to many people because it introduces more camera oriented experiences between the photographer and the act of connecting with the subject matter.
The discretionary (look or don't look) "instant" LCD feedback of DSLRs has changed. Sony EVFs now requires us to either set the camera so the "still image" feedback is in the finder and on the LCD (in the VF being extremely disorienting in faster paced shooting situations) … or set it to maintain constant live view in the VF, and we have to push a button to get the not so instant feedback on the LCD. Personally, that was a major interruption to the rhythm of shooting for me, and still is. I do not know if that can change. I hope so.
The gain and smearing of EVF in low light is also in dire need of improvement IMHO.
The other thing I hate is having to go into a menu to turn setting effects off, or turn it back on when shifting from ambient shooting to strobe use with a radio transmitter, which I do a lot at weddings and events. (I know I can short cut this operation, but it is still a separate act that has to be done). This is a MAJOR irritation compared to an OVF system. More complexity when I should just be shooting.
We'll see where it all goes.