They produce small pools of intense light.
They are spotlights, designed to highlight individual items in a display situation, and are totally unsuited to the job of evenly illuminating a whole room.
Unless you want your room illumination to be very uneven.
You yourself have recognised the problem with them:
we would need about 16 using 800 watts!
- You've realised that 800W of lighting for that room is crazy.
The problem does not stem from the use of halogen lamps, and therefore can't be fixed by switching to CFLs or LEDs, the problem stems from the shape of the cone of light emerging from a 50mm lamp with a parabolic reflector. Sure, you'd use less electricity with CFLd or LEDs, but only in comparison with incandescent MR16 lamps - if you compared the amount you'd need for proper illumination of the room and you'd find the same relative craziness - 16 CFLs is 176W, but the same amount of fluorescent lighting in a different format would be far too much, just as 800W of incandescent lighting in a different format would be far too much.
You said the ones I suggested were overkill - I'm not sure what's overkill about a few 200mm frosted glass discs "floating" just below the ceiling, so I'm probably not going to be able to point you at anything - all I can say is start looking for flush/recessed/surface luminaires designed from scratch to take fluorescent lamps other than the incandescent replacement formats with their own built-in control gear. Look at LED lights, again not the replacement format ones. Look at cold cathode. Look at induction lighting.
There are all sorts of alternatives out there.