Bootnodes are nice, they are something of a UX helper, making it easier for a brand new node to find peers.
If they are beefy enough, they can also help serve
eth data; state and blocks. Because of the amount of traffic (both egress and ingress), they are also pretty costly.
Are they terribly important to the network? In my opinion, no. Geth works fine without them, since more stable peers can be found via the dns discovery . The dns discovery is also centralized as in “it’s collected and published by EF”, but the information that is published is self-signed by the nodes themselves (in the form of ENR records).
Also, nodes (at least geth) remembers information about peers from previous runs.
In general though: If EF-controlled bootnodes are seens as ‘critical infrastructure’ then we should remove them, because the network needs to get by without central points of failure.