I’ve modified the comments form to require email addresses in comments. Some reasons:
When I get my email comment notifications, it sorts them by email address. When people don’t use an email, your comments become difficult for me to find in my email database. So, that is for my convenience.
Legitimate comments were being marked as spam, and I wouldn’t see them.
An email address is a soft version of a login. A commenter recently pointed out that “everybody is anonymous.” While that’s not completely true (I get quite a bit of info on my blog readers, and have few enough of them that it’s easy to sort out) this helps make it less so.
There are a number of ways on this website for people to contact me. The email in the comments is my way of contacting you. Your comments email is the email I’ll try to use, if I have multiple and old addresses for you. Giving your email makes this more of a two-sided conversation. I’ve never had a legitimate commenter who was uncomfortable with giving an email address.