It's not a dress code. It's just not adhering to another dress code. There's a difference. You don't just wear a suit RANDOMLY. Any random thing you wear is casual. Literally millions of different styles are casual, and there's like maybe five different styles of suits?
When I go out, I personally feel more comfortable in good looking, "business-casual" sort of clothes. That's generally a brown vest, some black pants and slightly fancy shirt, all of which I got for a total of 20 quid at a charity shop back in the UK. And yet, that set of clothes which probably costs less as a whole than the gaming shirt my buddy was wearing at the time got me an off-hand remark of "dressing up too fancy for a geek".
I'm very much a geek at heart and the guy knew it... but don't mistake the shirt-and-jeans culture for a "wear what you like" culture. It's a "wear what I like" culture, and the "what I like" is shirt and jeans.
Casual dress code does not include a clown costume, so it's far more constrained than your suggesting.
As to suits it's one of those fractal breakdowns with a lot of varity if you get specific enough. EX: You could say fat vs skinny ties, but the there is a wide range of patterns wich fit a wide range of shirt colors. Not just Red tie on white shirt.
Personally I like semi formal dress codes simply because they have a default and require minimal thought. Where casual has a lot of 'hidden' rules.
Actually, in the valley casual dress for men tends to consist of dark blue jeans, button down shirt, dress shoes, and blazer. It's as monotonous as tshirts/jeans/tennis shoes
Really? Wear a suit to your next startup interview and see what the negative reaction is. I worked at a company where anything other than jeans was frowned upon. You know what, in August I'd rather not wear jeans. Dress pants are way more comfortable (hint, they breath better).
A few years ago I was working for a west coast tech company (not bay area) and was regularly wearing long-sleeve button-down shirts (without a tie) with khaki pants.
A few coworkers said something to me, but I didn't think anything of it because (from my perspective) they didn't care about their own appearance. Then my boss told me that the company actually didn't have a dress code and I didn't need to dress like that; I assured him that I was dressed that way because I liked dressing that way. Then HR talked with me. That's when I finally took the hint.
The dress codes that most people are familiar with place a lower-bound on how you can dress. "No shoes, no shirt, no service", or "You're a groomsman, you can't show up to the wedding in a t-shirt you lunatic". The tech industry has a dress code, but it places an upper-bound on how you can dress.
My humble conspiracy theory? Upper-bound dress codes encourage social stratification. This is desired by people who are in power, but are surrounded by very clever and moderately well paid people (developers). Imagine if software developers stopped thinking of themselves as "others" and started assuming the role of respected professionals with all the social standing a respected professional typically gets.
Usually when you're new and don't already know the dress code, you show up 1 step above what you guess would be acceptable. Typically it's better to be over-dressed for a day or two rather than be under-dressed (fear or looking unprofessional/not serious).
