Also it provides lasting value in the items if they are unique/creative enough. Half the classes STILL want their epics (1.0 and/or 2.0) because these items were so well designed they kept their value despite being replaced as an equippable item.

1.0s were released in 2000 (14 years and 19 expansions ago)
2.0s were released in 2004 (10 years and 12 expansions ago)


Beastlord 2.0 - still a valuable burn clicky for pet (1.0 phased out soon as better weapons were avail likely due to class's late release)
Bard 2.0 - still valuable burn clicky for whole group (1.0 clicky wasn't replaced for many years)
Berserker 2.0 - still valuable burn clicky (same as bst 1.0)
Cleric 1.0 & 2.0 - valuable until they added the AA (which wasn't until like 10 years later). 2.0 still valuable as a emergency group heal.
Druid - both epics phased out sadly
Enchanter - both phased out 1.0 was extremely valuable for many years and 2.0 I think is still used but just not that fantastic.
Mage - 2.0 still used
Monk - 2.0 still valuable burn clicky
Necro - 2.0 still EQUIPPED
Pally - 2.0 still quite useful tanking CD
Ranger - 1.0 still a useful slow procing weapon and 2.0 still used as a dps CD
Rogue - 2.0 still used in burns
Shadow knight - 2.0 still a VERY useful group buff
Shaman - 2.0 still VERY important for group dps burns
Wizard - epic phased out
Warrior - 2.0 still used I believe but its pretty meh at this point