I work for what many would consider a very old-school, stuffy company. When we bring someone from the lab out to meet with customers we actually never tell them what to wear and we get developers showing up wearing everything from jeans to business casual with a sports coat. Customers never bat an eye either way. They’re developers, it’s expected they’re going to do what they’re going to do and we care more about what they say than what they wear.
At the end of the day we’d rather have the charismatic and articulate developer in jeans and a Green Lantern t-shirt vs the stumbling inarticulate guy in Brooks Brothers. And just as a side-comment since this is CC - this is an example of how social skills can affect the career of techies who might think it doesn’t matter. I’ve literally seen executives in my company say, “We’re never putting that guy in front of a customer again.” And that feedback gets back to the poor guy’s management. A couple college classes in debate and advanced English and participating in social clubs / activities in college helps out things like that. Emotional IQ and social skills really are a thing in the corporate world for everyone.