Why do we even need the date/time? The threads are in chronological order and each post is time-stamped anyway. Everyone has users whose posts they look out for, and if I've never heard of someone making a thread, it's gonna have to look interesting to make me view it. Quality control.
Showing my support for the "last post by user" fix if it's even a problem in the first place. It's not too bothersome, but it was more convenient the other way.