That's correct. Although looking into it more, it appears the revamps of the old world dungeons which made them much easier and less time consuming didn't happen until later expansions. (E.g Scarlet Monastery and Blackfatom Deeps two expansions later.)

Most of the revamps were done for Cataclysm.

But things were already being nerfed in Wrath -- For example, a Gnomeregan corpse run was of several minutes while an ICC corpse run lasted a few seconds.