Halo fans are not adrenaline junkies and they never were. In an attempt to appeal to the casual gamers 343 has forgotten what kept the true fans playing.
Halo has always been a tactical shooter. The biggest factors of this tactical gameplay were spawn timers, static weapon spawns, and formidable vehicles.
Spawn times punished players for dying, and gave them enough time to regroup and restrategize. Enemy encounters were constantly changing in-game because players were always changing their tactics. This made Halo feel fresh and replayable.
Static weapon spawns encouraged map control. Everybody knew exactly where the rocket spawned, and there was a constant struggle for the power weapons. This brought some variety, and flavor to any gametype.
Vehicles were always powerful, and they should remain so. It was so much fun racking up kills in a warthog gunner, or feeling like a bad -Yoink- in the drivers seat. Banshee was even more powerful, but it stressed the importance of power weapon control, and forced the player to change his game-plan.
Modern gamers are so intent on dumbing everything down in an attempt to “balance” the game (I call it the socialization of video games). Experienced gamers know that the most balanced games are the least fun. If everything is balanced, then the gameplay is stale.
Imbalance adds variety, it encourages teamwork(coordinating attacks on the all-powerful banshee), and most of all… It forces us to think differently, to be constantly aware, and be willing to change our approach.
This is why HCE, 2, and 3 managed to keep our attention for about 5 years each.
Except for CE, people still play that. 