so core devs control all the nodes and miners now

Core devs control the code that ~85% of the network nodes elect to run. This is presently Bitcoin's greatest point of centralization.
Right. So it wouldn't be unreasonable that Gavin would would ask for "only" 75% consensus to offset the status quo bias.
At least in my opinion.
This is more conflation of decentralization of "development" vs. that of the protocol. Consensus refers to the protocol -- not the node client. That the development process is centralized is absolutely no excuse to compromise the basic, basic principle of consensus. 75% to hard fork is 75%, no matter how you rationalize it.