Except when it shouldn't: multi-line textboxes (such as those on a "Contact Us" or "Description" box) need the ability to let the user hit Enter without the form being submitted.
Sure, and that's the way it works by default: In a <textarea> Enter adds a new line - in a single-line <input> Enter submits the form.
What I'm saying is that if you have a single-line <input> field and pressing Enter doesn't submit the form, you should add some HTML/JS to ensure that Enter submits the form.
What I'm saying is that if you have a single-line <input> field and pressing Enter doesn't submit the form, you should add some HTML/JS to ensure that Enter submits the form.