The pace of invention today is based on iteration, building upon other successes and similar ideas - and its happening in real-time across a vast community. This is awesome.

Personally, I love that we have choices like derby, meteor and potentially, sail. Every effort has pro's / con's that may or may not be ideal for a particular use case. I would rather have more options than none.

Ever tried GWT? I played with it a bit. It gives you One Language -- Java -- and does a pretty good job of it. It comes the closest to accomplishing what the author is talking about.

Unfortunately it puts this huge condom between you and the web medium itself, making design nuance difficult to achieve. But if I had to write, say, an accounting app for a car rental agency I would seriously look at it. It would be a great way to create a solid, stable web thin client app.