And you *need* javascript to store cookies, how?
I haven't thoroughly debugged the scripts on Chase.com, but let me offer a few guesses. Only script can store cookies in localStorage or IndexedDB. Only script can generate a keypair that the server and the browser will use for challenges and responses, and only script can respond to the server's challenges.
And all it does is make pages more cluttered
JavaScript lets a web page hide a particular element until the user expresses interest in viewing it
Requiring extra clicks to read content I could've been reading right away, taking my attention off the act of reading and onto the act of finding what silly tab to click.
Are you familiar with the concepts of "information overload" and "progressive disclosure"? Please look them up on DuckDuckGo before proceeding. The gist is that if a document presents far more information at a time than the user is expecting, the user will find it difficult to find the desired information in the document. An alternate model is to present the entire web site as a single document and use the web browser to navigate in that document, but that's the same model that PDF uses for navigation, and a lot of Slashdot users have voiced their hatred of various things about PDF.
Does it now? Have you measured that, down to the extra handshakes?
It doesn't matter. One handshake to start a download of the 4 kilobytes of information that has can changed and one handshake to start a redownload of the entire page are each one handshake. One of them just transfers less data afterward. Besides, HTTP/1.1 allows a web browser to hold a connection open, resulting in fewer TCP handshakes overall. I myself have not measured that down to the extra handshake, but operators of large web applications have. There are white papers on the Web about on how Yahoo! and Google optimized their web applications to require fewer requests.
It already starts out bad with sometimes huge background images and avatars and all sorts of other crap that you're supposed to be interested in
Which would be sent with or without script. In fact, without script, more things would have to be sent and re-sent.