About the syntax/name convention: even if this is not a rilevant point, for people coming from Blitz3d the 'old syntax' is - of course - a benefit
It's also easier to port old code. Ordering the docs by category is the logical choice anyway, even if using the other method (you could have other commands falling in the same category but which are not directly related to a set, i.e. it would be silly to have all math related commands starting with "Math", such as MathSin() instead of Sin(), or every network command preceded by "Directplay"... tidier but longer to write for a basic language, which should also have more resemblance to english).
I use a modified version of the help in B3D myself where all the categories are expanded, and it is surely much more easy to search than max's help. :) (for Max as well it would help to have the command reference with all the official modules and their commands as an expanded list on the left)
However I usually write my libraries with the Category_Instruction structure (also to differentiate my commands from the main ones), so I'm used to it either way.