Aside of personal preference, I haven't read any reason that show any detriment to Superman being able to travel through time. Other characters have the ability to travel through time, and it isn't an issue, why does Superman need to be kept from the power of time travel, when it would allow for more avenues of storytelling?
The last good Superman time travel story I read was "Time and Time Again". Superman traveled through time, and there weren't any ill effects to the story, the character, or the reader.
Let Superman be super.
I just do mot gey this compliant of him being too powerful, like Thor and Silver Surfer aren't?