I can explain it from the programmer's viewpoint.
Text, help files, and instruction manuals are boring. Programmers do not find them interesting and therefore skimp on the "debugging" of simple English. It is many times the most tedious part of programming a finish product for the general public.
With that said, any programmer would welcome a grammarian picking over their mistakes at this point in the Beta. These are simple fixes and gives you a sense of accomplishment to fix these bugs, when most of the bugs at this point are getting harder to find and more difficult to fix.
I would +1 a thread dedicated to spelling and grammar only.