English proficiency is really low in the Russian speaking world relatively. So you gain access to communication with lots of people you wouldnt otherwise be able to. When you learn a language like French you are just learning how to speak to people you already could speak to just in a different language.
It can teach you things about English. Those features you speak of were in the ancestor of English too. Plenty of cognates too
Baltic and Slavic languages are much more conservative languages than the Romance and Germanic. You can learn a lot about what kind of features European languages had historically by looking at the Baltic and Slavic languages.