There's nothing intelligent about positional requirements so it can't be "dumbed down" since it was never "smart" in the first place. The only thing positional requirements create is frustration due to latency differences between players. The positional requirements are fine in PvE because you're not trying to hit a moving target. In PvP they don't work the majority of the time unless some form of CC is used.

If they were to change how casting interruption works they could easily change interrupts to be on shorter cool-downs. I do agree with you that casters shouldn't be able to just free cast but the current system isn't the right way to go about it. It takes no thought to interrupt casts and it doesn't feel right. They should have just copied the way PvP works in WoW. It just feels right compared to this clunky system we currently have in place.