We can't expect the Germans not to use the event as a bit of a road test, given that it was indeed designed to be that. Other countries are allowed to field youthful "development" squads when it suits them, so why not. Even though many of their squad players are inexperienced internationally, they are not fringe players with their clubs. Unlike the members of many other national teams, these German players are pretty much all regular players at a good level in a strong league.
I've not got a problem with them using fringe players, they have the right to pick whoever they want, it's more the whole attitude of the German FA (and related names such as Rummenigge) seemingly undermining the tournament at every available opportunity.
The fact that they won't take a full allocation of players when they easily have the means to is a proverbial middle finger to the tournament they're playing in (we care about this so little we're not going to bother bringing a full squad)
, their own 'fringe fringe' players (we'd rather leave the slots empty than take you as backup)
, and their chances of winning (IIRC there was a match at Euro 2008 where due to suspensions/injuries Turkey had only a couple over 11 players left to choose from, if something like that happened to this German team it would have taken 2 less incidents to get there)
, although that last part has unfortunately been proven wrong by whatever they have in the water that makes them go deep into tournaments regardless (visiting Munich for a few days in a month's time, if I come back with a driven winner's mentality you'll know what happened)
The only passable excuse they have for not calling up replacements is that whole 'maintain squad chemistry' angle, but by their own admission it's a development squad that's unlikely to be the core of any future side, so I'm failing to see many positives from their decision (aside from possibly giving Sane and Demme the easiest medals of their careers, as FIFA still list them as squad members but 'absent').
Back on Rummenigge, matter of fact I'll take my previous comparison to Farage
a step further and suggest that this has the makings of a German football version of Brexit* (Confexit?). The establishment of a country are pointing out faults (fabricated or otherwise) in a harmless but generally positive external international thing they're part of in an attempt to distract from their own controversies (2006 World Cup bidding) while making little attempt to help improve said external thing from the inside, in the meantime actively undermining it with the help of a semi-related mascot claiming to speak for the masses but is really in it for their own gain and not even pretending to hide it that much.* = Feels like I've been here before...