I don’t want buttons in my emails.
You could have a larger text instead of a button, but changing font size is also HTML and not plain-text anymore.
Those templates should account for all types of people and accessibility levels (including things like ADHD, where you need a big red button to click, otherwise you get overwhelmed by a block of text).
I don't think so. I certainly didn't have to resort to HTML to make that link readable and clickable.