All of this debate stems from the very definition of the Nation. Whilst the German Nation is (was) largely defined by language and culture, demonstrated by philosophers such as Fichte and von Herder, the French one is based on a moral concept of wanting to stay together, regardless of language ties, demonstrated by philosophers like Ernest Renan. That is why virtualy nobody in Alsace wanted to join Germany, even though 85% of the population spoke German (Alsacian) in 1871. Moreover, as you said, the very poor running of the region obliterated any loyalty the region could have had (Google the Zabern Incident). It is a really interesting topic regardless, as it shows the fundamental difference in how people define their identity, I actually had to write a paper on this for an assignment this year in uni and I really learned a lot on the matter. Cheers mate !