Would love to know what your writing that requires specifically assembly knowledge.
Just a matter of having at least some remote clue as to what a computer actually
is - y'know, it's a thingy that fetches an instruction, resolves addresses, manuipulates multipexors, that sort of stuff - I found that having had a few lectures and an exercise on assembler at college was a reasonable proxy (I only insisted on educational exposure to assembler, not on having written it for a living).
Performance is a blindingly obvious example - one line of
VB (or any other modern high level language) can take thousands or millions of times as long to execute as another similar looking line, and someone who has not the remotest idea what might be going on under the hood is simply not going to understand this and design and code accordingly.
Of course a C++ (non-managed) programmer is going to come across real assembler in real life quite often, being every time that stepping through the source using the debugger doesn't find the problem and it's necessary to step through at assembler level. I still wouldn't, of course, require anyone to have written x86 assembler for real! - it's much too horrible. (Personally the last time I wrote thousands of lines of assembler was for the 68000.)