I would say that 5E was built with a fair amount of flexibility with the design goal of allowing 3PP to integrate in. It provides a structure that allows a decent amount of options and add-ons like level up.
Of course it's not the "modular system" some people envisioned, there will never be enough flexibility for some people.
Of course it's not the "modular system" some people envisioned, there will never be enough flexibility for some people.