*snip*
Imagine having to save each private key separately? I have dozens of addresses, I would go crazy
It is even bad for security and privacy, as we would have an incentive to reuse addresses to avoid saving more private keys.
Definitely underrated. Far more important than SegWit in my opinion. I expect a lot more people to answer SegWit here in this thread.
There can be more upgrades if network will be more friendly to updates
If you need to make sure that Bitcoin will be as secure and as bug-free as possible, we need to be extra extra strict with update proposals. If you want upgrades that are "more friendly", or those upgrades that are mainly just decided and automatically pushed by just a few people, go with centralized altcoins.
Some level of centralization definitely has its advantages over pure decentralization. Besides, there are plenty of entities and people within Bitcoin that exert a considerable amount of soft influence over the entire ecosystem. It is done more in narrative formation than anything but that is still real power if people fall for it hook, line, and sinker.