They are not imbalanced. It has to do with level progression. At
the end of the day, 60 epics are just... level 60.
Typically, my understanding is that you can already find better
greens/blues when venturing into Outlands for the 1st time, if you
have Tier 1.
Tier 2 you will feel the obsolence about 64-66.
Tier 3 is comparable to the new Tier 4. If you have your Tier 3,
you can skip obtaining Tier 4.
Tier 4 is the 'new Tier 0', where you can obtain it quite easily.
The purpose of T4 is to allow players that did not have the ability
to obtain T3, to get equivalent gear.
Players would tend use Tier 3 or Tier 4 to leapfrog to obtain Tier
5 gear.
So it really sucks if you only have Tier 1, because it is almost
worthless in BC. With Tier 2, you can make use it of it for a good
time. Tier 3 would be comfy all the way to 68-70, although you
might be peppering blues into your gear choice.
I logged in the other day, and man, are flying mounts amazing. So
many level 70s flying around. Beautiful.
