It would be quite appreciated to see an immediate effect spell that didn't have to be aimed and couldn't be shield blocked. It is magic. It doesn't need to physically manifest and then travel between point a and b.
But blewis17 is right and it is likely due to screen presentation of large fight scenes, so there isn't the focus on the magic being prepped and then the closeup of the unblockable and invisible effect taking hold. I have the distinct feeling that riceball would agree (always has a good grasp of why for screenplay choices).
I agree, with some enthusiasm, that it begs the question "Who needs Hokey religions and ancient weapons when you have a good blaster at your side."
But then on the other hand: one of several things about the SW sequel trilogy and Rogue One is adding sound effects to The Force in use... the sudden woosh and hard sound stop, so you "know" it is at work. Was never required in the OT or PT as I recall.