I think RSS needs fixing first before building anything on top of it. At the risk of that xkcd meme about 15 competing standards, RSS + images is a total mess. Every reader supports different ways of rendering images. Sometimes it's inline HTML, sometimes it's the RSS <enclosure> element, sometimes its something entirely else.
Some readers either support <enclosure> or instead load inexplicably tiny/blown up/stretched/pixelated images, or just don't display any images at all.
Consider that podcasts use RSS - yet need a special namespace "itunes" in order to work:
<itunes:duration>30:00</itunes:duration>