That would be a fine argument if we'd been seeing this superiority of engines for years, but it's the first year the engines are out. Next year manufacturers can change 48% of the engine. That's 48% of things they got wrong, they can change. How much could they have possibly gotten wrong? I could understand if this was the second year where Mercedes was showing this level of superiority, but not even mid way through the first season the crying began.
I think the moving next year's freeze to July is a decent compromise on the part of Mercedes.
The complexity of the situation is that Mercedes has to cough up the most money simply because the other manufacturers got it very wrong. Merc supply four teams, two cars each, that's 8 engines. Renault is down to two teams, Honda has one team and Ferrari three teams to supply. Mercedes has 40 engines to build for the season! The costs do add up when you change something.
it's also not practical if there's a newer spec engine and a team saved an early season engine to use later on. It makes the early engine obsolete, again money being thrown away by the customer teams. There was a valid reason the teams all agreed to do this in the first place.

So enough with the unsportsmanship crap, we put up with four years of Red Bull skirting regulations with AD voodoo, we put up with laughable stewarding and ridiculous double points ideas, the point is the sport survived the bore fest of 2011 and 2013, and the borefest of 99 ~2004 it can survive the inferior engine design teams catching up over the next two years.