The problem is ISPs are already interfering with your traffic. Try typing in
a non-existent domain name for instance in the web address bar. Chances are
you'll be redirected to an ISP web page. This violates the standards. Try
downloading a torrent. It's likely you'll discover somebody it throttling
your traffic. Maybe it won't happen right away, but it happens in a lot of
scenarios. From university networks, to commercial ISPs (Comcast), to
cellular-based "internet" service providers.
The question is probably more along the lines of a level of maliciousness.
I'd like to think my ISP is not doing anything malicious, but the reality is
otherwise. Many ISPs try and force you to install malicious software. They
fraudulently return IP address for domains that don't exist. They inject code
into web pages, torrents, etc. to cause disconnects, profit off your eyeballs
(advertising), cut costs, etc.
Even software we generally respect includes features that leak data that may
be privacy-sensitive. I believe both Canonical's Ubuntu and Google Chrome are
good examples of this.
