I've been learning Vietnamese for a few years and it seems to just fine without all the complicated tenses and cases etc in the grammar of European languages. I'm not sure if all those baroque rules really buy much.
They don't buy anything, but they don't cause any problems either. If they did, the language would have changed to accommodate it, or died out already. But since you're putting the effort in to learn it as it is, clearly neither applies...
The languages have changed - English used to have a more complex grammar (thee, thine, thou, etc) and I think it had genders, but that died out over time.
