In my opinion, centralized exchanges/platforms should exist but shouldn't be promoted too much or above decentralized platforms for the sake of decentralization and security of cryptocurrency. The crypto communities should be promoting the decentralized platforms. The outside world could choose to promote what they want.

I think any cryptocurrency that has most of its value on centralized platforms shouldn't be seen as very decentralized.. Most of tradings should be happening peer-to-peer or via decentralized platforms. The point is to keep things censorship resistant, immutable, secure, trustless etc. Centralized usage of cryptos shouldn't be more than 40%...the less the better.