Well, you'd have to redo many things in bitcoin.  So many, actually, that almost nothing would be left of bitcoin.  Your question is akin to "if flying in the air is so important, why did people build airplanes, and didn't add wings to cars which were already riding ?".  There's so much to change in a car to turn it into an airplane, that it is easier to start off from scratch.

That said, I repeated already a few times, that a good way to introduce a new coin is not to start a new chain with a new genesis block, but to fork off bitcoin, to give every bitcoin owner some of the new coins (something like the eth/etc fork) ; except that the fork is so drastic that only the "original ownership of bitcoin" is kept, and nothing else of it.

As to why one shouldn't bend to the core dev's foundation, I would think that in crypto, that's evident, no ?  There is no authority.