They actually are labeled; I 100% agree with you. Unfortunately, as far as I'm aware, I can't label the button as "pre-order" without making it so that nobody can download anything. If I switch to "pre-order", it assumes all the files I'm uploading are placeholders and doesn't let you download anything. If I'm mistaken and you know how to make it show "pre-order" on itch.io, please let me know and I'll switch all applicable projects to show pre-order.
-Emily