I've been experiencing issues with clients that insist on using the button tag for buttons. But this is currently not possible. And using a html embed everytime you want to import a button is not a sustainable solution.
But I can imagine people still want to use the <a> tag when adding a button for different kinds of reasons.
So my suggestion is to bring the "Tag" option into the Button Settings. Where you'll be able to select the following options:
A (link)
Button
Bram Huinink
.svg){kind=logo}