Well considering this was a game to rest starters to some extent i'd actually opt for Villa to get a chance as CF instead of Cesc as a false 9. This gives more chances for Tello/Deulo/Cuenca to play and Villa can guide them and bail them out if necessary. Also since Villa rarely ever gets to play as CF, it would boost his confidence and allow him good practice to keep his finishing sharp and improve his ability to drift into the middle and make smart attacking runs when messi drops back a bit as a false 9. Also Cesc gets a rest or could play alongside Thiago in midfield so that Thiago gets more chances to improve as the "boss of the entire midfield" rather than playing more advanced.
I agree with that. This was a pretty easy game and what you said would have made sense. But in reply to what messi_xavi_iniesta said,
in general terms, Villa LW + Cesc false9 > Villa CF + second/third-choice wingers. Besides, Barca's mentality is to do their best, even against Segunda Division teams. At least until they're in a comfortable position, that's why they played the better option in the first half, to secure a lead with the more dangerous combination, then Cesc went off in the second. Perfect tactics.