Reach had the potential for high numbers of enemies (to demonstrate my point, this is something I was working on sometime before I gave up on Reach. These are almost all the AI that can spawn in the map at this point. I did not add them in).
It’s just that Reach had horrendous difficulty balancing, which made it impossible to utilize such large numbers in an encounter due to the severity of the enemy AI:
-overwhelm us with large numbers of varied enemies (CE, Halo 2) or give us a couple of Jackals with haxed plasma pistols or Elites spamming explosives (Reach)
-give us multiple badasses or tough guys to fight (CE Zealots, CE Hunters) or put a bunch of high ranking enemies in 1 single boss setting (Reach: LNoS hangar Ultra Elites, PoA Zealots)
-give us a wave battle that progresses over time regardless of our involvement (CE Halo rockslide battle, T&R boarding battle, Halo 2 Cairo Station hangar battles), a fast paced wave battle (T&R grav lift battle), or a slow paced wave battle (Reach: LNoS hangar, The Package glacier, PoA Brutes)
The enemy numbers were minimal skirmishes and encounters were mediocre, only tough because of unfair advantages.
Enemy numbers were tried and true in CE, which had simple yet sufficiently convincing AI. Whereas:
Halo 2 introduced higher damage, weak player, redundant ranks (Ultra Elites replaced Zealots, Ultra Grunts, Grunt Heavy) that were damage sponges, and increased enemy aggression.
Halo 3 gave the damage sponge attributes to every enemy and increased enemy aggression. Though it nerfed Jackal snipers.
Reach made the enemies more tougher (Grunt Ultras have helmets, Elite majors can survive a grenade stick, Hunters can take multiple rockets) and increased enemy aggression.
This pattern needs to end. Halo campaign difficulty has barely progressed beyond primitive aggression. Intelligence should be the #1 prioritization.