Evidentials

I don't really believe in languages with obligatory tense. I prefer a comprehensive set of tenses, aspects, moods, and evidentials in a language, and they're all optional for use.

In an optimal language, there should be a comprehensive set of tenses, aspects, moods, and evidentials—TAME—which are all optional for use. Whether they would be expressed as verbal conjugations or particles to complement invariant verbs is a question of architectural design.