Just out of curiosity, I looked at the HN RSS feed and they still use regular escape for titles (and some other things, except description). It means they use 2 versions of escape instead of 1. So why not just use 1?
What requirments are you talking about? Human readability? IMHO, RSS is for feed readers, not humans. When looking at https://news.ycombinator.com/rss , the RSS isn't that human friendly at all, all line breaks are removed. The point is the simplicity and uniformity, regular escape works well for many cases, not just description.
The description contains HTML markup, such as <p></p> for paragraph breaks. CDATA is a nice and clean way to encode them without breaking anything.
The title doesn't contain any markup, and shouldn't. A good old escape function covers both the "doesn't" part and the "shouldn't" part.