I made the analogy between Spain and the Germans on the Eastern Front in WWII merely as a proxy. It was made to compare the harshness of the occupation not the reasons. I know dang straight that N did not go into Spain with the intention to rape and pillage. Hitler went into Russia with that intention. The French went into Spain with "good" intentions were met with resistance, reciprocated with brutality, met with more brutality, reacted etc. etc.
However comparing the effects of these occupations an analogy can be drawn. The sieges in Spain were as brutal as those in the 1940s (if not for the same reasons). The effects on the populations were also similar. In Charles Esdaile's book "The Peninsular War" he states that Spain lost a million people, more than 10% of the population as a result of the war. Portugal lost 10-15%. These numbers show the brutality of the war, may not be all the French soldiers' fault, but there is no denying the effects.
As for the War of Liberation, I do not feel that it was a sheer nationalistic uprising, but there certainly was the desire to kick the French out. In Bourgogne's book he talks about when the army retreated through Prussia after the Russian campaign that he was met with much hostility by the population. The fact that the Saxons turned on N at Leipzig despite their King remaining allied shows something as well.