Larger format (D)LSRs used to always have the advantage of a bigger viewfinder, which was great. I still remember the peephole of my first DX Nikon DSLR after coming from a Minolta film body. It was horrible, but limited by the size of the mirror are of less. Electronic viewfinders are no longer tied to the sensor (or mirror) size, so that advantage is gone.
The other advantage of "full frame" over APSC size is familiarity (SLRs) and legacy lenses (mirrorless). The later will diminish over time as people don't have legacy lenses (I don't). However, while all specs are quoted (somewhat arbitrarily) as 35mm equivalents, people will always think it is the standard size and it will be both familiar and something to aim for.
But, while I think APSC is a great compromise like most others, Fuji is the last company to take it seriously, possibly the only company to ever take it seriously. Canon, Nikon, and Sony all put out tentative APSC cameras with weak lens lineups and have since shown their hands, deciding that full frame is where it is. Pentax has continues to put out APSC lenses but also have their "professional" full frame camera. Panasonic has made the same move: full frame is professional.
So, we essentially have Olympus and Fuji as the only companies putting out a range from amateur to professional in a sensor size smaller than full frame. Is that healthy? On one hand they have a monopoly in their fields, on the other they are trying to be competitive with cameras using larger sensors. I hope their will to be competitive with larger formats leads them to highlight the advantages of smaller formats. Olympus does this very will with IBIS - a smaller sensor is easier to move than a bigger one. Olympus and Fuji both both do this with a full range of appropriate size and weight lenses, which are proportionally smaller that their full frame equivalents.