Randomly generated loot

Launch -
Level cap was 10, what was most sought after by players was clean level 8/9 randomly generated loot such as +4 stat items that dropped in Giant Caves, Co6 elite and Tempest's Spine. Items such as +1 "Power Five" (Vorpal, Paralyzing, Banishing, of Smiting, of Disruption) weapons, +5 stat items (with race restriction or lesser durability) and +1 Stat Tomes existed, but was extremely rare. Pearl of Power VIII to X was considered high end as well.

Module 3
Demon Sands (October 2006). Level cap increased to 12. Level 10/11 loot was becoming somewhat common but was still quite rare. We started seeing level 11 +5 stat items more commonly in Black Anvil Mines runs, which was introduced in previous Module 2.2 but it was tough at level 10 cap and we didn't see many PuG runs until the level cap raise in this module.

Module 4 - 5
Reaver's Bane (April 2007). Level cap was increased to 14. "Power Fives" were becoming very common at this point. Almost every single melee characters we saw in PuGs carried various types of them and Giant Skeletons in PoP got disrupted almost instantly.

Module 6 -
The Thirteenth Eclipse (January 2008). Level cap was increased to 16. Green Steel items and other named items started overshadowing random loot. Level 13 +6 stat items were still popular but what melee characters used was GS weapons, Power Fives, or occasional Greater Banes and nothing else. Item cap was increased to 16 but the only place you could get them was Shroud Elite which was almost never run since there was no additional ingredient drop.

Module 9
Aka Eberron Unlimited (September 2009). Level cap was increased to 20. Item cap remained at 16. We started seeing level 16 items commonly but stat item didn't go any further than +6. Random loot at this point was completely overshadowed by Green Steel and various raid loot. Only thing people hoped to drop in random chest was Wounding/Puncturing and Holy Silver Greater Bane.

Update 1 -
The first Epic contents introduced (Demon Sands). Item cap was increased to 20, however, it only lasted for several weeks of its launch. Chest ransack counter in new Epic quests were not functioning and players started to farming Against the Demon Queen to make some plat income and stock of Epic Seals. Turbine fixed the counter and lowered item cap to 16 in response to this. This level 16 item cap continued throughout all Epic contents up to Update 13 Web of Chaos.

Update 14 -
Menace of the Underdark (June 2012). Level cap increased to epic level 25. Item cap increased to 24/25.
 * See
 * Update 14 named items
 * Composed weapon affixes
 * Update 15 named items

Somewhere around U16:

Update 19
Shadowfell Conspiracy (August 2013). Level cap increased to 28. Item cap increased to 28 as well. At highest level what we saw was +10/+9 or +10/+10 (with Masterful Craftsmanship).
 * See Update 19 named items

After U19, randomly generated loot was getting in the process of somewhat-overhauled by a developer named Feather of the Sun, a person seen in the above video, but things went south and Ghostbane weapons were dropping way too frequently.

Update 29
The Codex War (December 2015). Level cap increased to 30. Item cap increased to 30 as well.
 * See Update 29 randomly generated loot.