CDATA sections are just for the convenience of human authors, not for programs. ThereTheir only use is to give humans the ability to easily include e.g. svgSVG example code in a xhtmlan XHTML page without needing to carefully replacing every << with << and so on.
That is for me the intended use. Not to make the resulting document a few bytes smaller because you can use << instead of <<.
Also again taking the sample from above (svgSVG code in xhtml) it makes it easy for me to check the source code of the xhtmlXHTML file and just copy-paste the svgSVG code out without again needing to back-replace << with <<.