You wrote that it had changed "recently", which initially had me slightly confused. The Math Library section of context-sensitive menus was all rewritten between Maple 9 and 9.5. That's when this change to the order came about, I believe. That development was done in late 2003, so about 4.5 years ago.
The rewrite work was done by a former student of yours, if I recall. Not that you had anything to do with it, of course. But you could ask the author, if you need more details about either the decision to change the item order or about other changes in it.
We know that it also slowed down, both with the rewrite and with the advent of Java in the GUI. Some performance improvements have been made in Maple 12, especially with regard to the speed of generating the context-menus for large Matrices, but also in some other ways. Naturally, we would like to find the resources for making it faster still.
I'm writing here about the performance of the Library-side code that generates the menus on the fly for a given object. The speed of Java for doing its part (especially for the very first menu's initialization) is a whole other GUI aspect from my perspective.
If you see context-menu items that you think are wrong, please do submit them. Thanks.
Mathematical Software, Maplesoft