I don't like a lot of them but sometimes they're needed for the site.
For example I'm working on one site now where a modal lets you sign in (which involves selecting from or searching through a long list of third parties) and if it wasn't a modal it would have to take you to a new page which would be a poor UX.
So long as they're not used for those awful "sign up for our mailing list" purposes, have been set up to work well on all browsers and viewport sizes, and are accessible, I think they can be okay.
My argument to that would be simply that you are wrong.
A new page is the correct UX design choice and with HTML5 features can make the experience seamless and far less jarring than a modal that needs heaps of testing to get right across all browsers and screen forms.
But that was essentially my original point. Modals, when used by sign up to spam are annoying. When used to do anything else they're essentially trying to replicate a desktop experience that quite frankly isn't required of a website - even on "web 2.0" or full on web applications.
Also, please link an example of a modal done well across all browsers / screen sizes. I simply have never seen one in the wild that works better than an inline page element would have.
