I know a similar question has been brought up before, but I'd like to add my perspective to it.
We are running an ecourse site and all our student interactions are in the forum without any access to the WP backend. I know the member list only searches for display names, which isn't all that useful to our users. It would be great if they could also search by first and last name, perhaps even email. The reason for that is that students are often curious if anyone they know is taking a class.
I am on the fence about searching by email address as it's one of the more sensitive pieces of information (we had students concerned/confused because their email address shows up on their profile when they look at it and we had to explain it's only visible to them). Though it's also one of the most definite options to find someone specific.
First and last name would be great though. Is there any possibility of having this added or can search already be modified in that regard?