Needless to say, there are countless network protocols which leaves no room for maneuvering when it comes to implementation, you ever heard of anyone coming up with their own version of SSL/TLS protocol?
When the ISP's will be decentralized then it will be possible, which is only a thing yet to come.
I`m sure the SSL/TLS can be improved too, just like anything.
But you also have to factor in the risks of improving somethings, vs the safety of leaving the old protocol.
So even if the bitcoin protocol is outdated, I`d prefer to not risk an update of it, and to break more things.
A protocol must stay simple, and must have a capacity in it to be scaleable. And then just build on it.
Changing a core protocol is like changing a constitution. Never a good idea
Those that want to do it are either: cowboys, tyrants, or fools.
Nontheless, not the good people.