My suggestions:
- Make average ilvl weighted according to the stat budget of each slot, perhaps with some extra weight on weapon
- In addition to minimum average ilvl, add a minimum single item ilvl (should be somewhat lower than the minimum average so that players are not forced to upgrade all items too often, especially when working through 5.x)
- Add ilvl requirements to the "leveling" trials
- Make roulettes have an ilvl requirement equal to the highest relevant content for which the character level requirement is met (for example a Lv70 character queueing for alliance raids would need to have i365 gear; this prevents ilvl cheesing)