Why introduce spartan III's into Halo reach when they could have used II's?
To allow for something new and to fit the lore. The story line for the Spartan II`s at this time was about as fleshed out as it possibly could have been. Suddenly starting to throw them around all over the place when they are just about to go kidnap a Prophet from High Charity would have been a lore fuck.
Why was nobel team the only spartan team on reach?
But they were not the only Spartan team on Reach... Echo and Gauntlet team were just before the glassing of new Alexandria mentioned as having been redeployed to civilian evacuation.
There is also a group of 13 dead Spartans (II´s or III`s is anyones guess) located near the Aszod ship yards.
Jorge is confirmed to be a spartan II, where are the other spartans?
Getting their Mark V suits and about to go on a trip to High Charity.
MC is shown in cryo on the autumn. why wasn't he fighting?
He had just been fighting aboard that space station and destroying the navigation core or whatever they did up there in "The Fall of Reach". Also, thats a total easter egg. The cryo tube was not located in the hangar bay...
Bungie screwed up. They were to busy making a final game to make a solid plot.
If Bungie screwed anything up then it was the multiplayer map design. The story was among the best the Halo series has seen.