Hi!
It would be great to have a possibility to register on an event, even if you are NOT going to attend. In some use cases, it is necessary to know which members have considered attending and then given their registration (either "Yes" or "No").
I implemented this for myself by using an extra field "attending". This unfortunately still leads to many manual code hacks, if want to see the "real" number of total attendants in some views. Thanks for your update, this extra field can now be inserted in the registrant list!
Maybe you should consider inserting this into the core (without using a custom field)? This is probably not a top priority thing to do, but maybe sometime!
Have a nice day!