Following instructions

When I receive solicitations from freelance translators seeking work, I respond asking them to "send your résumé/CV and a brief sample of your work INTO your native or dominant language, with original, enclosed in a StuffIt or Zip archive, using your last name as the filename." I find that only about 15% of respondents actually follow the instructions. It seems like such a simple thing, but apparently it's not. How reasonable is it for me to reject out of hand the respondents who send their CV and sample unzipped, or don't use their last name as the filename? Is the ability to follow simple instructions in a situation like this a good predictor of ability to deal with more complex ones in a paying assignment? Or would I be passing up a lot of capable, talented people by arbitrarily eliminating the ones who fail this test?