The Cage. The fence the octagon's wide corners/pylons and the size of the cage all make it hard to see
With a to ring there are ropes. Viewing the fighters through ropes is easy easier. The wide octogon corners block the view as well. Then you add in the size. If the fighters r on the opposite side it's to far too see. Especially when you consider that the judges are pretty much eye level with the mat
Hopefully one day the cage will become a thing off the incompetent past 
You know they have monitors in front of them at UFC fights to see better 
JTA710 - You know they have monitors in front of them at UFC fights to see better
Not at every venue
There should be x5 judges...? Maybe.1/2pt system w/ "damage" being second only to "finishing the fight"..? Possibly.
I personally cant wait until the 1st & 2nd generation of fighters/coaches, etc start filling the judging slots. Its only a matter of time.