HTML controls vs. ASP.net controls

I recently discovered that if you only use html controls with no <Form></Form> tag, you can access the controls in javascript directly. However if you use asp.net controls which automatically inserts the form tag, you have to use document.getelementbyid
My question is, besides the advancements of asp.net controls, is there another benefit to using server side controls even though they are ultimately rendered as html controls?
Another question would be, wouldn't it be efficient and enhance development time to use html control and no form tag where a lot javascript is involved? (I know jQuery is a revolution in this area. My question is more in the realm of maintenance.)
Adam
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