Some aren't used to the idea but fairy switching has always been rather strategic, and with the addition of Dissipation there is even more emphasis on it. You should never stick with the "I summoned this fairy, we are sticking with it" ordeal.

In extreme/savage level fights you should never have to hard cast a fairy. It'd also be pretty silly to blame your death to a movement mechanic because you wanted to be safe and "hold" your swift but yet not get into position on-time. Swiftcast saves even your own life. You just have to look at the skill as a toolbox.