imo the first question should be: which features do we want to represent by noun/verb endings and which do we want to represent by modal verbs/adverbs/etc
e.g. latin conveys person, number, tense, mood (indicative/subjunctive/imperative), and voice (active/passive) in its verb endings, while english conveys most of these via modal verbs ("will" etc)
I definitely think that the amount of helping/modal verbs in English is excessive and that doing as much as we can through endings is ideal. However, simplicity is always the goal, so we may take whatever measures necessary to achieve ease and simplicity
