Can't even blame them on that; that's business.
But right now it's a cheap source of games from a program that was so desperate to get the exposure that they agreed to take whatever time slots ESPN needs filled. Right now ESPN has a sweetheart deal with BYU, and BYU took it because they wanted exposure (I've long argued here that our next step isn't getting on national TV -which is no longer rare-, but getting on decent channels at decent times.) So of course ESPN likes that. And for right now, that means ESPN likes BYU getting attention. Since they own BYU inventory, it's good if people watch BYU games.
But there's zero loyalty or ongoing investment in BYU. BYU just isn't big enough in the grand scheme of things to drive major ESPN decisions and as soon as there is better or cheaper flexible inventory, ESPN would just as happily take that.