What BS. If I'm going to apply for a new job, I'm not about to use my current, "professional looking" e-mail address from my current company for any correspondence, that is just asking for trouble.
What's BS? You doubt that hiring committees pick apart every detail of an application? I'm not saying that a free email address alone would ever be grounds for not hiring a candidate, but it is one of many small parts of the story the candidate weaves about his/herself.
And in the design world (note thread title) there are enough candidates with domains and websites with portfolios. The candidate with a gmail address risks getting lapped by the competition.
When the first cut of applicants reduces the field from 24 to 8 based upon nothing more than the application, you can't afford any missteps. If you wonder why you aren't getting called into any interview, this may be one (of many) reasons.