Good point... if I really trust the source or care about the material I'll use my main email. If it's a service that I feel may be spammy I'll use a generic email address I keep around for that.
When I REALLY don't want to put an email in and have to, it's the typical "[email protected]"
Definitely - competition played a huge role in making text message plans cheaper. With 1 less network that's available for consumers to choose from kills other chances of networks introducing agressive pricing, etc.