The technology for all the monitoring and safety processes is neat on these amps....and the 'catch' with solid state finals. You simply MUST have all these control circuits or your finals will go 'poof'. That's what costs so much with these.
Do a bang for the buck comparison with something like an AL-1500 or even the higher end amps like Acom or OM-2500 and it becomes a really difficult thing to justify just to avoid tuning up a tube amp...which with just a bit of practice just takes seconds to do.
Some guys are afraid of tubes for some reason and that is what I believe is driving the market.
If you compare the Yaesu Quadra or Icom PW-1, they have lower power but are rated at full duty cycle unlike many other solid state units and they have full integration with their designed rig pairings giving essentially a kW transceiver because the integration is so slick. With a system that well integrated I can see a bit more benefit, particularly if someone is an obsessed contester.
Until you get full protection circuitry integrated into base power modules, high power at solid state will continue to be an expensive and very proprietary proposition. One thing to note, if those control boards die on the smaller manufacturer's amps, you are tied to them for replacements....with Emtron as an example, they just leave their customers sitting in the dust with no parts, with Alpha as an example, they take care of you but at 1/3 the cost of a new amp. So you pay $6k+ for an amp, lose a board and it costs you another $1500...because you are basically stuck buying from the one source.
Even the higher priced tubes are nowhere near that expensive to replace.