Privacy is a necessary feature in my opinion, but why hasn't Monero become a main coin?
Monero is genius, it does everything you require from a privacy coin. Unfortunately its strengths have led to its downfall in the hopes of becoming a main coin. Governments hate it & regulators have threatened exchanges with operating bans in their jurisdictions if they list XMR. That has meant exchanges have delisted XMR & that’s the reason why the price isn’t as high as it should be.
It’s a great coin for anonymity but it will never be a main coin sadly.