We like to think the Nords the underdog against the oppressive, racist Thalmor who want to destroy their religion, but do you really think the Nords would be any different if the situation were reversed?
The primary difference which influences a lot of the way that we perceive the Nords is that wiping out the Mer is not a mythological goal of humankind as it is in the case of the Thalmor. Essentially, the Nords are inclined to commit war crimes against the Mer because of a longstanding war/divide going back to Lorkhan and Auri-El. Systematic, planned out genocide, however, is not a feature of Nordic ideology. It is more based on fighting over the ideological dispute of Aurbis-CHIM vs. return to Aetherius/the state-of-being of the ancestors, plus thousands of years of warfare/revenge so that no one on the Nordic side even knows what they're fighting about anymore.
Similar, but not synonymous.
[EDIT]: Also note that the resentment of the Chimer was originally begun when they stopped Lorkhan from retrieving his Heart at Red Mountain. But then, I doubt that the Nords would have just peacefully walked in and taken it either...