Hoodies have become as much a standard of conformity as suits. You're just conforming to an unspoken requirement to appear sufficiently non-conformist.

Show up in such an environment wearing a suit and see how much your self-expression is valued.

I've worked at one of the big Bay Area software companies with a guy who wore a suit every day. If I wore one at my current (non-US) company, people might ask me about it for a few days, but I'm pretty sure it'd become the new normal within a week.