Since auto growing and shrinking of textareas is not possible without JS the editors are currently set to a fixed size. This might lead to annoyingly and irritating empty space for, e.g. one-line paragraphs.
This could be avoided by roughly guessing a fitting size when building the elements in PHP and setting the textarea heights accordingly. The rough idea would be to have 3 size levels ( small, medium, big ) that could be applied. - In the JS version these heights will be overridden by the flexible height calculation.