Yeah I certainly wouldn't waste a precious FIFA window on such a game, esp this year in leadup to important qualifiers.
However it would have been useful say straight after the Confeds Cup - when most of the AWs 1st eleven just needed a rest - to give these fringe players a game in front of Hudson and his playing staff.
For example Mexico actually had 2 teams playing at the same time as the Confeds Cup was on. First team played Portugal in 3rd-4th playoff, on same day as another Mexico national side were playing a friendly in USA!! That must only help build their playing depth.
Another opportunity to play a type of 'B' international game for fringe players, would be after our playoff series against 5th South American team. Presuming we lose those playoffs and don't qualify for next World Cup, might as well play fringe players in following friendlies.
Little benefit in having European big guns play those friendlies, given next World Cup qualifying cycle won't start until 2019 onwards - plus being in the midst of the heavy European season schedule they will probably be unavailable anyway (likes of Smith/Reid may even retire from international football).