Knowing the order of answers coming in is pretty valuable to me.
Even three weeks later, being able to see the date and time in comparison with the other posts is useful to me. I admit that I may be an unusual case but you've failed to show what harm it does, so even a small benefit to some makes it of value.
Think about this... I ask a question... and then I disappear for a week. I come back to the site and there are two answers posted on the same day... they're very similar and they both solve my problem. I want to accept one of them but I can't choose between them... so I decide that I'll pick the older of the two... but they were posted the same day.
Yes, I can hover over the date on each to figure out which is older... but many users don't realize that feature exists. So, as it is now, I can easily see which is older, even if only by a minute or two.
For that reason, I think this should not be changed.