The SEC is represented by 12 of the top 23 teams in the nation in RPI this season, and the 13th SEC team is ranked 34th. 11 of them are in the top 20.
The Regionals won't offer that kind of competition, and the WCWS will be hard pressed to equal it. I imagine the committee took that into heavy consideration.
The top 4 SEC teams this season were UF, UGA, USC, and UT. Both UGA and USC played UF while not facing each other, and UT faced each of those teams but only met UF once in the SECT. UT lost to UGA at home in a series, and were swept by USC in Columbia. Both UGA and USC had better conference records than UT did.
In RPI, UT was 8th, UGA 10th, and USC right behind at 11th. But I'm thinking the committee placed greater weight on the conference schedule RPI as opposed to say, the non-conference RPI during February and March. Had the SEC been a weaker conference, then it could've been the opposite - sort of like what UConn in WBB has to deal with every year.
But there is no reason to look months in the past when SEC teams have to play in a meat grinder every season, at the end of the season and closest to tournament time. IMO, even though overall UT has the better RPI then both UGA and USC, if one were able to split the SEC-schedule RPI from the rest of the season, then UGA and USC would be ahead of UT. And that's how the seeding ended up....