Separate pages vs dynamic content loading

Many web applications use some kind of dynamic content loading via jQuery or AJAX nowadays instead of just linking to new separate pages, letting the user navigate through the web page without really switching to another site. Often this kind of web technology seems to be faster, because requesting something with a smaller foot print (like JSON encoded data) is faster and therefore better for site performance.

But a lot of web projects prefer the "old styled" model: You link to another pages, if the user navigate to another page a whole HTML file is requested from the server.

What are the pros and cons for both cases? What is, in your opinion, the right way for modern web applications?

Please note that's not about static vs. dynamic pages or client-side frameworks vs. server-side frameworks or the combination of them. It's just about your perspective about this topic in general.

Thanks in advance.