Bob the Squirrel doing a face-plant off the helmet.
But I seem to recall him saying at one point that he wanted to be an astronaut when he was a kid. Which makes the suit a little more interesting. I'm not going to spend a lot of time playing armchair psychologist here, trying to suss out if he's harboring some long-repressed regret for signing up for the regular science class in high school instead of the AP one, but I am reminded of the maxim: "Dress for the job you want, not the job you have."
I can't seem to find the origin of the phrase, but I know I saw it in ready circulation last year with an addendum about wearing a Batman costume.
Of course, the phrase isn't meant to be taken precisely literally. Wearing a space suit or a superhero cape alone doesn't get you your dream job. The phrase is more metaphorical. You need to see yourself in whatever role you're attempting to get into before you actually step into it, and to make that step, you need to convince others that you're prepared for it. You need to show the people who might elect to put you in that role that they may as well put you in that role because you're as good as in there already. You think the way you need to, you act the way you need to and, yes, you dress the way you need to.
In the field of comics these days, there's fortunately a pretty minimal dress code for creators. But how you dress still affects how you're treated. You ever see fans come up and talk to Seth in person? There's a distinctly different tone and style than when fans come up to, say, Mark Waid. Waid's appearance is not that far removed from most fans, while Seth tends to look like he stepped out of a 1930's accountant's office. Consequently, fans tend to address Waid more casually.
Some of it is personality and attitude, of course, but creators' appearance is both a reflection of that and a signal to others how they want to be seen. Take a look at pictures of notable comic book creators. Robert Crumb, Jim Steranko, Stan Lee, Lynda Barry, Frank Miller, Art Spiegelman... They don't wear uniforms per se, but they showcase a distinctive style every time they go out. And I know in at least half of those cases I just cited, that's very conscious and deliberate. That's part of who they are, and how they're treated.
As a creator, you certainly can go around wearing jeans and a t-shirt with your favorite superhero on it, and it's not a huge deal. But now that we're living in a particularly media-savvy age, I think your appearance has more of an impact on how you're received by both fans and other professionals. You maybe don't need to go to the lengths that James Sime does, but just throwing on whatever happens to be in your closet seems like less and less of a viable option any more.