Are you American? Do you know the history behind blackface? If not, I'd recommend you to actually do some research before comparing both things.
And it shouldn't be a matter of is it "way too much". Either it's wrong or right. In this case, everything is the former.
I don't think you even need to be American or understand Blackface to understand the basic premise that one's ethnicity is not a costume.

Halloween doesn't give you the liberty to dress offensively. I'm sure that's the thin thread these partygoers are desperately hanging to, but it's not a valid one at all.