It seems like the need for using the word "just" comes from the fact that the US has a culture of not offending others, and because people have a hard time divorcing their work from their worth as a person.

It's hard not to do it, too. I can be looking at code from a coworker, and I can't just say "Hey, this method sucks, can you redo so that [reasons]" because it will be a hostile work environment. Instead I would have to go in a roundabout way and say something like "Hey, for this method, wouldn't it be better to have it do x instead of z".

Or when trying to set up a meeting with someone you want to impress, like I'm a startup founder and the person is a potential investor, I will want to use softer words and suck up to the person a little. I can't say "Hey, I'm flying to SF on Tuesday to meet you", I would have to say "Hey, I'll be in SF on Tuesday, would you be able to meet?".

I don't necessarily think it's bad, it's just how people navigate through the accepted behavior of our time/country/industry/office.