Anything can be improved — but in Cuil's case, yes, it would have required reversing pretty much every decision they made (or at least implementing them on such a different level they would be unrecognizable). It was just breathtakingly ill-advised. DuckDuckGo is more clear about the benefits it offers, modest though they may be, and it follows through on its boasts. And Blekko is just modest all around.

I said at the time and still say that Cuill released a very early stage experiment that still hadn't worked out what it wanted to do and called it a search engine.