It would be useful if we had the ability to either create an opportunity without an email address or to change the address once it has been created. Many times I'll get a call and start tracking my notes on it, but since I may not have an email address for the customer yet, I'll use mine since one is required or make up a fake one for the customer. The problem with either solution is that once I find the customers email address (this could be days later), I'd like to attach that opportunity to the customer.
You can now freely edit the e-mail address of any Opportunity (for the record, you still cannot create one without an address).
Note that during a fresh entry the address does not appear to be pre-filled anymore and there is nothing in place to force you to fill it in before submission. There's no consequences other than the entry not being created, but the worklist does "crash/disappear" temporarily and you need to refresh the tab/menu to bring it back.
If there's enough usability complaints about people forgetting the address, we'll open a new separate request for that.