>Did historians put in this much work to highlight the
>inaccuracies in "Lincoln"?

yes.

http://www.slate.com/blogs/browbeat/2012/11/09/lincoln_historical_accuracy_sorting_fact_from_fiction_in_the_steven_spielberg.html

http://www.thedailybeast.com/articles/2012/11/22/what-s-true-and-false-in-lincoln-movie.html

http://www.theatlantic.com/entertainment/archive/2012/11/fact-checking-lincoln-lincolns-mostly-realistic-his-advisers-arent/265073/

http://www.newyorker.com/news/hendrik-hertzberg/lincoln-v-lincoln

http://www.npr.org/2012/11/22/165671751/we-ask-a-historian-just-how-accurate-is-lincoln

http://www.thenation.com/blog/171461/trouble-steven-spielbergs-lincoln