DC doesn't operate on the same kind of timeline that Marvel does. In the Marvel Universe, if you travel back in time and change something, you create a new alternate reality that then has no bearing on your own. In DC, time travel can actually change things. So Booster Gold goes back, saves the President and then... what? Doesn't that severely screw up about half of Skeets' records right there? Even novice chrononauts know that if you go back and prevent the Titanic from sinking, we wouldn't have the stock market crash or the Great Depression - changing history is a pebble in the pool. Wouldn't Skeets have to go back to the future every so often to refresh his headlines? And why wouldn't Booster warn his friends about the really bad stuff?
"By the way, Superman, tomorrow you're going to get beaten to death by a thing named Doomsday, and almost everyone we know will get mangled in the process. You could probably throw his prison into the sun before he gets out, though. And hey, that might stop Hal Jordan from flipping out and murdering 3,599 of his fellow Green Lanterns, then trying to restart time. Oh, and someone might want to keep an eye on Jean Loring, too."
Actually, that's what happened between Countdown and Infinite Crisis - fed up that he'd let such bad things happen to his friends, Booster took Skeets back to the 25th Century and they studied up. For instance, in the original history, Batman never found the cloaked Brother Eye satellite - but by recruiting the new Blue Beetle, he saved the day.
So see, kids? It pays to stay awake in history class.
Actually, that problem has been addressed. Apparently, the time period that Booster arrived is a sort of time-data blackout period. According to the few times its addressed in Booster's original series, much of their historical information has been lost or garbled.
I seem to think that even the Legion is unclear what happens during this time.
Anyway, at the end of "Infinite Crisis"/start of "52" he zips to the future to try to get more complete data on DCU Present. For the most part his data ends up being quite lousy, but at the very least, the Blackout period seems to be ending.