Sometimes we take heat for deliberately not implementing certain Web platform features. Three significant examples are SVG Fonts, WebSQLDatabase and H.264 in <video>.
SVG Fonts --- at least the subset implemented in Opera and Webkit --- don't offer anything significant over downloadable Opentype (or WOFF) fonts ... except the last three points of the Acid3 test :-(. And people keep asking for it "because it's in SVG 1.1". But I don't think those are good enough reasons on their own to make SVG Fonts an essential part of the Web platform.
WebSQLDatabase has a completely different problem. It's the only way of doing structured, queryable client-side storage in any browser right now, and a lot of mobile apps targeting Webkit-based browsers use it. The problem with WebSQLDatabase is that it isn't good for the Web, because it depends completely to the semantics and query planning of SQL as implemented by SQLite --- which is a somewhat quirky SQL implementation.
The pros and cons of H.264 have been well documented in this blog and elsewhere...
I think not implementing certain features is one of the hardest and most altruistic things we do.
Update I should also point out that we're not just exerting "stop energy" here; for each of these features that we're not adding, we are promoting superior alternatives --- namely WOFF, IndexedDB, and WebM.