[ashray]

You're right. But the fact that jQuery has a much simpler API than using just javascript makes it easier for programmers to use it. It's a library and that's what libraries are for, it takes care of notorious cross browser compatibility issues (how well is another question..)

jQuery UI similarly helps implement features such as autocomplete, etc. which while you could take the time to implement again offers a simpler API with cross browser tested code.

I don't think there's any argument against the fact that jQuery has definitely made a massive impact on the use of javascript on the web. There are plenty of programmers who wouldn't touch javascript with a 10 foot pole before jQuery due to the cross browser issues. I think that's actually been a good thing for UI for the most part.

Can it be done faster and better ? Yes.

Can it be done cheaper ? Probably no.