Anyone with visual basic, xml and database understanding can create a macro-like tool to help the data editor.
My argument is simply that the time and effort spent into creating this tool will far outweigh the potential benefit it brings to a map-maker. Especially since every patch has caused one or another feature of a 'work-in-progress' map to break unexpectedly.
It's a fine balance between customizability and comprehension, really... and Blizzard's developers took the route of ultimate customizability...
I'm pretty sure we've had this argument before
... With any creative based software (3D Studio Max, Blender, Maya, Photoshop, UDK, Mudbox, Sculptris, Unity etc), the more customisability and subsequently, power, you are given - the road to learning that software increases exponentially in difficulty.
Imagine if creating high poly 3D next-gen models and textures, fully animated and unique - was as easy as dragging a few sliders and clicking a couple buttons. And if coding multi-layered API jazz was akin to writing sentences for the program to carry out... The entire game industry would collapse, because every tom, dick and harry could create games.
To bring this back to the context of SC2... Blizzard cannot tick all the boxes. You can do pretty much anything with the galaxy editor, and most of it is easy - but as a trade-off for this, a lot of it is complex and long-winded and involves a higher level of understanding. I would say that of all the mapping communities out there, only about 40% of the editors true potential has been unlocked - and this is reflected in the popularity system, by the high proportion of cloned, boring, ultimately predictable games on there.
Regardless, it is without a doubt the most powerful standalone modding tool I have ever come across (excluding UDK since that's design-focussed). If you really like, I can put more effort into explaining how the data editor works. I've managed to get camstudio working so I can also finally record that video series I was toying with ages ago.
None.