Edit2: Please pay attention that this post was written in august.
Haven't noticed anyone mentioning this yet, so I decided to make a post about it. The biggest problem with the epic Dragonwrath questline is that it doesnt contain a quest which would take long time to complete. This means that for good guilds it will take about 4 weeks for the next person to finnish the questline and even for normal-mode guilds about 5 weeks for the next person to finnish the questline. This probably means that Dragonwrath will become surprisingly, one of the most commonly used weapons, if not the most common among raiders in 4.2 (even in 4.3).
It's kinda late for Blizzard to change things anymore, but the issue might affect majorly how things will be in 4.3. Personally I think this will mean either:
1. Casters are going to get major nerfs or melee are going to get major buffs. Which screws the balance among casters who does not have Dragonwrath.
2. No major nerfs or buffs occur, melee are being subbed for people with dragonwrath. Top guilds with alt runs steamroll new raids with over 10 dpsers who have the legendary.
3. "You cant use more than 3 Dragonwraths in a raidinstance or you will disturb the magical blah blah" etc. So more than 3 people cant wear it at the same time.
4. They will nerf Dragonwrath or make the new raid drop like 422 ilevel gear even on normal mode.
Edit: It takes far more than 4 weeks for the first player to get the staff, I know. The problem is that people are already on the last part of the questchain when the first player has received the staff which means you will get a new staff every 3-6 depending the amount of hardmodes.