If you were to always fetch your data using an SQL pass-through would you really need .mas or .acx files?

To my understanding you only need these file if you were to do a TABLE FILE tablename.

I have tested this on a Windows server running WebFOCUS 5.2.6 and looks like it works fine without them. Has anyone else tried this?

you are correct, you don't need them if you're not using them!