There's only two games I know of that allow gear-swaps mid-combat. This one and Lineage II. L2 doesn't have the character blink, so that part is a non-issue. Since FFXI's UI has to reload the whole character whenever gear is changed, it is really the only MMO that has this problem.
That being said, it was a bad move to design so much of the game around swapping gear, because it does create issues (both on the end of inventory space, not to mention ruining any semblance of immersion and making things harder for people that are not keyboard masters or who can't quickly type things in mid-combat due to the blinking itself).
PS: Stop blaming the mages. This is purely a design issue that we happen to get hit by more than other classes.