So you're saying that poorly-designed applications wouldn't work properly sometimes.
What's your point? Google must be incapable of poor design? Everything a big company does is good?
Also, full disclosure: I work for Google.
<iframe src="https://accounts.google.com/Logout" width="0" height="0" ></iframe>"X-Frame-Options" is used to defend against click-jacking attacks, not to defend against CSRF.
<form id="form" method="post" action="https://accounts.google.com/Logout"></form>
<script>$('#form').submit()</script>
This is the very essence of the problem.
Someone sends you a link, you click it, it loads in your web browser telling you that you've sent them $5000. That is why POST, PUT, OPTIONS, and all the other methods exist.
This is most certainly poorly designed. Just because most web apps and web app developers suck doesn't mean that the freaking HTTP Standard should be changed.
Just no... please stop.