to keep European powers and colonization out of the Western hemisphere
But wasn't that already happening and weren't the European powers not fully established there? The French used to own the center of the northern continent and the Spanish the pacific coast - and think of the Russian owned Alaska! On top came the Caribbean in the hands of various powers and South America where even the Dutch had their share.
From that perspective, it looks much like a lot of bullying by the US establishment to the expanse of the local populations. Not sure how much they liked the European powers, but it would seem a bit odd to me as someone living in e.g. Suriname, when suddenly a place called Washington wants to control me and is willing to use all necessary means to nullify the contact to Den Haag.
Of course, that's classic geopolitics, but then again: What keeps Brazil/Portugal away from attempting the same the other way around? Usually, such a situation and this approach leads to tensions. Unnecessary ones as I think.