Depends. There are advantages and disadvantages to having the whole ‘Kasus, Numerus, Genus’ stuff around. To put it simple, if it was so bad than why is it still around in so many languages?

From a scientific point of view, one of the advantages is that it introduces redundancies (e.g. when adjective and the corresponding noun have the same suffix) and differences between the different syntactical parts of a sentence. This makes it easier to understand what someone else is saying even if you misunderstood them.

For the same reason computers exchange messages not simply by exchanging ASCII code because a single bit flip would alter the messages meaning.

You also need to keep in mind that languages weren’t designed to be easy to learn for non-native speakers. They have been developed by native-speakers simply using it.