SEC Bowl Advantages
First off, let me say that in the history of the two schools Ohio State and LSU, that they have played twice. Ohio State has won once and they have tied once. Of course, that was back in the late 1980's when OSU was incredibly average (4-6-1 and 6-4-1), but LSU was really pretty good (8-4 and 10-1-1).
Now, for the main reason that SEC schools do better in the bowls than the Big 10.
1. Scheduling. LSU had a bye week Oct 27. The Big 10 does not schedule bye weeks for any school. Also, the Big 10 does not have a conference tournament as other conferences do. I personally am in favor of no conference tournaments. The football season is already too long - adding one or two games at the end of the season only keeps the players away from their studies that many more weeks. The tournament games are played on neutral fields, so there is travel for all teams involved in the tournament. And after all, aren't all of the players on the field granted athletic SCHOLARSHIPS? It's not athletic gift aid, it's SCHOLARSHIPS.
Anyway... this means that every Big 10 school will have a longer layoff before a bowl game than it's SEC counterpart. Longer layoff means a longer time to lose your mental edge.
2. Weather. The reason that games are not scheduled as late in the Big 10 is that the conference is geographically farther north. I live in Iowa and last weekend in the Division III tournament, Central played in conditions like this: http://www.pictureprints.net/albums.php?gallery=1961
Although it would be interesting for Ohio State to host LSU on this coming January 8. There is no way that LSU could simulate the weather of Columbus in January. They play on those dates in the pros at venues colder than Columbus (New England, Buffalo, Green Bay to name three), so why not in college?
3. Geography. The BCS bowls are all played in the south. Not necessarily the southeast, but the south. Easier access for the SEC fans. Let's see, Ohio State has to travel about 900 miles from Columbus to New Orleans (where the championship game is this year). LSU has to go about 80 miles from Baton Rouge. Closer = easier access for your fans, especially the students. In fact, LSU is closer to every one of the BCS game locations than OSU.