The TP cost for sprint in PvE is both balanced and a positive addition to the game.

The PvP change is not an indication that the skill is unbalanced in PvE. Skills get PvP-only balance changes all the time because these environments are so different. For example, Repose was nerfed for PvP, that doesnt make it overpowered for PvE. It's one of the more useless skills. In the context of PvP, sprint allows players to engage/disengage. In PvE, sprint is almost solely about repositioning.

It is balanced because melee characters have a front-loaded attack and can move while attacking. For example, assume you activate a skill, need to move out of an AoE, and move back.
Without Sprint:
Castor: interrupts cast, moves, starts casting, hits
Melee: attack hits, moves, moves again, hits

With sprint:
Castor: finishes cast, sprints, starts casting, hits
Melee: attack hits, moves, moves again, hits
(not to mention, the melee character has more survivability if they do get hit)

If you want to make the argument that the TP cost should be removed, it needs to be in the context of the PvE environment. What benefits would it have? pros/cons/etc?

Personally, I think it is good that sprinting is discouraged with the TP cost, because it adds several positive things to the game:
* Swiftsong and other movement speed increases have additional value.
* Healers can sprint ahead to pickup keys and unlock gates for their tanks.
* A pickup group is less likely to get split because of sprint activations and cooldowns.