Any other professional environment I disagree. Why? I wear crocs to work. I wish I could go barefoot. What does footwear have to do with software development?
When business came about, there was a general idea that the quality of a person and their business dealings was reflected in the way they presented themselves. This was a big deal back when you had to physically interact with the businessperson. If their appearance was sloppy, cheap, unclean, or otherwise with no care put into it, often the products would reflect the same lack of care.
Fast forward to present-day. Joe Emacs sits in his Herman Miller, his "No, I Will Not Fix Your Computer" t-shirt stained by cheetos and free mountain dew. His sandals expose his grimy, untrimmed, twisted toenails. He smells of BO, either because he forgot to put on deodorant or hasn't showered in days, probably due to "marathon coding sessions". His hair is also greasy and smells.
Joe Emacs likes to shout over his cube to his co-workers, because why should he make the effort to get up? Joe Emacs likes to leave trash all over his cube. Joe Emacs blares youtube clips over speakers instead of headphones, annoying all his co-workers, preventing them from working. Joe Emacs likes to talk loudly about subjects that bother or annoy his co-workers. Joe Emacs is an asshole.
Compare Joe Emacs to Fred Altair. He comes to work in crisply ironed chinos and a dress-shirt or polo. His hair is combed. He smells nice. His brown leather shoes gleam in the fluorescent light. His desk is neat and tidy. He walks over to his co-workers and politely asks questions without interrupting. He uses headphones, and doesn't discuss religion, politics, or other controversial topics in the workplace.
It doesn't matter which you would prefer to be. Joe Emacs is going to annoy his co-workers and make it a shitty place to work. Fred Altair will be appreciated by his co-workers, and make it a much more relaxing place to work.
But it's not about clothes. It's about professional attitude and environment, which is to say, respecting your co-workers and not becoming a burden on others. If you can do that while still wearing Crocs, by all means go ahead.
Barefoot is just not acceptable. it's unhygenic. Nobody wants to smell your feet, and even if your feet aren't smelly, you're at risk of developing a fungal infection, injury, etc. Wear some shoes.
The other aspect to picking a particular style or dress (let's call it "conservative dress") is that it makes people more comfortable. People are weird. Often they get uncomfortable if people around them dress different than they're used to. You see it in tech workers all the time: they say "I'll never wear a tie! Oppression!" or somesuch thing. Ties make them uncomfortable, just like people in shorts, sandals and a t-shirt with a slogan might make other people uncomfortable. Something in the middle would make everyone more comfortable, which makes for a better work environment.
But the way you dress can influence the way you and your co-workers behave. In my experience, dressing more relaxed leads to more relaxed personalities, which has both great and horrible side-effects. People think they can act however they would with their friends, which (for tech types) might be very abrasive to strangers. It may also affect their work, or how they compose themselves in meetings. I can't tell you how often i've heard the causally-dressed guy tell someone to fuck off in a meeting, while the guy in business-casual is much more tactful. These are just some examples.
After about 20 years in professional work, I can confirm that the nicer the suit, the bigger the asshole. The hack is to dress in a nice suit as well and then don't back down when the bully bombasts all over you. You'll probably end up with a promotion. Not backing down form a T-shirt position will probably get you laid off.
> I wear crocs to work.