The two expressions are similar but not completely equivalent. "Let's skip the formalities" is something you may say in a formal context. For instance, you're talking with your boss and you say "Let's skip the formalities: are you giving me the axe? (= are you firing me?)". Formalities are a series of rules and conventions you follow especially in formal contexts. The other expression ("to come straight to the point") is more general and means "to say what is most important right away". It doesn't necessarily mean "skip the formalities". Maybe your friend is afraid that you'll get mad at him and he or she is "beating around the bushes" (which is the opposite of getting to the point).