I am not stating BLU's spells are not powerful where applicable, but you cannot say there are no drawbacks to them. If you are meleeing with Almace on Blu you aren't spending anywhere near half of your time casting spells or being asked to cast spells (maybe if you're tanking I suppose). If you are CW burning you aren't even using a sword most of the time except for trials.

VW is a situation where you would have to swap spells mid fight, and it is a giant hindrance to BLU.