If you're going to disconnect both the HTML and style sheet from your Marketo instance, why not just upload a regular web-page on your main site? I guess I don't see why you would still want to use a landing page w/o using any of the landing page streamlining features. You can always embed Mkto forms on your custom pages (as we do on occasion) when you need more flexibility.
I agree with this one. We are a marketing agency that builds out landing pages and emails for our clients. We often don't even have access to the client's website to be able to build a landing page there.
It would be great if you could view the full source code of a landing page after you assigned a template to it the way you can with emails. This way your template is more of a base starting point that you could modify.