I cannot explain
why the jQuery team decided to make the scale of the UI elements so large. And I agree with you - it seems too large!
The team has made it easy, and intentional, for developers to roll a custom jQuery UI theme. This is available as a graphical option in the jQuery UI download section and allows you to edit the dimensions of all things via their friendly graphical interface.
In the "theme" section at the bottom of the "download" tab of the jQuery UI website, click on the small link entitled "design a custom theme". In the page that opens, you can easily adjust all parameters and still have everything presented to you as a single download.
Hope that helps.
Regards,
Alan
