"Not keeping the Blu feel" is the lesser evil. Blu simply can't operate inside regular content because regular content is balanced around the holy trinity.
A class that can casually swap between the three roles simply can't exist in content like that without either
A. Being broken, or B. Being nerfed into the ground.

If Blu was nerfed into the ground it wouldn't be fun so they went the opposite direction. The whole class is an experiment.

Outside those two options Blu would need to be entirely reworked or they would need to rework everything that was balanced around the trinity.
(Which wouldn't be so bad if they had future proof labels attached to their data/codes but they probably don't.)