Texas A&M played ASU in Houston. WE play LSU in Houston in '17.
Alabama played Wisconsin in Arlington this year and plays USC in Arlington next year. Auburn plays Oregon in Arlington in '19.
Houston to the Big 12 would help to re-claim the Houston market and recruiting grounds. Get Oklahoma, Texas, Baylor, TCU, Oklahoma St., etc. into Houston - much more often than the SEC.
Houston is also a solid program that is showing commitment to growing. Brand new stadium, putting $3 million+ on a head coach. Content is king, and Houston will provide solid content. "New" markets only matter for conference television network subscriber fees - and that model is changing - see ESPN.
And, btw, although Memphis is a top-5 college football market (in terms of ratings in the Memphis market), it still has fewer viewers than Houston. Houston has 2.3 million TV households; Memphis has 636K. So a 3.0 rating in Memphis is similar to a 1.0 rating in Houston.
Good move IMO.