Just for grins I opened up my CD of recorded maps from the year 2000. Randomly opening about 50 of them (I wasn't counting) I found that those created in LDT (I know they were, based on that funky North Arrow and/or having knowledge of the office) all had leading zeros for the degrees...expected since LDT has most always done this. Those offices still doing things by hand (yes, there still are!) were pretty much split on the use of them. Those using other CAD software used both methods, but leaned toward the use-the-zero side.
So the majority use the leading zero, but, so far as I can find, there is nothing that says they MUST be used. I have always used them, but it doesn't bother me when I see a map without them. That being said, I do think that the option should be there to use as one desires, but in no way would I let it affect my decision to use the software.....it would be, and has been, classified by me as a minor annoyance.