For those who get irritated at this kind of thing, "Like" is another example.

I don't see any reason Feeling tgat way. Little decorations that may not add meaning, but do add texture. And they can change meaning.

"Then" is another example - like "so" it can be added at the front or back of a remark. And front or back makes a difference. At the beginning it can make it sound like a command, at the end it sounds more like a sugegestion. "So would you like a cup of tea?" Seems to imply "Make up your mind- I haven't all day". "Would you like a cup of tea, so?" somehow doesn't have that hidden sense. The same difference seems to be implied by the positioning of "Then" - "Then have you made your decision?. Or "have you made your decision then?"