Considering the amount of precision mechanics required for gyros the cost of a few flat panels should be well below the old steam gauges. Perhaps that is one more reason why they're the primary choice with manufacturers. But I'm sure the main motivator is the market.
Aside from that, modern electronics are quite reliable and some of the solutions available provide a high degree of backup.
I haven't actually flown behind the Garmin or Avidyne solutions so I don't know how they'll work in flight, but the Garmin panel I have seen does look a bit cluttered with a lot of information. Still, it's supposed to provide the basic 6 (T) primary flight instruments in a similar grouping. Surely, anyone training to become an airline pilot should benefit from this setup!
With regards to the quality of the electronics, I have heard numerous reports of avionics reboots in Embraer aircraft sporting Collins equipment. You'd expect them to be pretty stable, they cost more than a small aircraft!! Software issues no doubt, but still...
I hope the "Radio Shack" equipment we'll be flying in our little planes are more reliable than that!
