Winter Contingency: No. This jump starts the whole game. [agreed.]
Sword Base: Yes. The events of this level are pure action. Set up coms, defend ****, etc. [agreed.]
Nightfall: I still don’t know what we were doing in this level, so definite yes. [There was an entire section of the continent blacked out to satellite surveillance, etc. Noble team splits into recon teams to locate both the source of the blockage and the (rather obvious to infer) base in the area. This is where we learn how the Covenant got onto Reach in such large numbers without anyone noticing.]
Tip of the Spear: Yes. Blah blah take out a shield protecting some covenant thing. Again pure action and no plot at all. [agreed.]
Long Night of solace: Yes. Blah Blah, blow up some covenant ship which is totally unimportant. Again, pure action and no plot. [The Covenant ship you call totally unimportant is a supercarrier the likes of which the Battle of New Mombasa surrounds
completely. It is also responsible for a large portion of the Covenant ground troops and Command and Control for same. Also, Jorge dies. Behold! Plot!]
Exudus: Yes. Blah Blah, get civilians out of the city. Notice how the plot hasn’t advanced AT ALL since meeting with Halsey.
New Alexandria: Yes. Blah Blah destroy some com jammers. The game’s almost over, and the plot STILL hasn’t advanced since level 2.
The package: No. Finally, the plot moves. We learn we need to get Cortana to Keyes on the Autumn..
Pillar of Autumn: No. It’s the climax.
Notice how in Halo, the plot is steadily advancing all throughout the game? Now notice in Reach, how only the very beginning, and the very end of the game move the story forward at all?