Simplification of inflectional endings has been an ongoing trend for thousands of years. For example, if you were to compare the language spoken in Norway, Sweden, or Denmark in 1000 AD with Icelandic in 1000 AD, the languages would be essentially identical. However, over the last thousand years, isolated Iceland has retained its extensive noun and adjective inflections (four cases in both singular and plural) and its endings for verb conjugation. It has preserved the past. By contrast, Norwegian, Swedish, and Danish - countries not isolated at all - have streamlined (reduced) their inflections greatly. English has done the same.