What's the point of expressing plurality of nouns by modifying the word?
Solution 1:
I believe you answered your own question in your opening paragraph.
First, I am certainly aware that language is dynamic and English, like all languages, has been constructed over time by usage and culture and hasn't been "engineered". English is what it is because language is dynamic and it evolves over time because of common use and cultural shifts.
I don't mean to be dismissive. I just genuinely don't understand what other sort of answer you might be looking for.