I know where you are coming from, but having had their fingers burned (read incinerated ! ) with the 787/ Dreamliner, Boeing were thinking that medium term, & finally, with a little more fuel efficiency , the FLUF is fine, so go for the cheap option(as indeed Airbus have done finally? with their similar "solution") Why not ? nobody has enough spare cash to re-invent the wheel at the moment.
Forgot to say, for 737/320 family rated guys, rejoice! it wil be
same airframe /same rating = less opportunity to be shafted by an accountant