Accept it
In my humble opinion, you used all the arguments that count.
If management judges that the downside to the current situation is less important to them then the advantages (if any) then you need to learn to live with it.
Remember, it's not your network, it's theirs. And you are there for the sole purpose to keep THEIR network running.
If you can not do that given the requirements by management it's your job to let them know the downside to their choices.
But if they are willing to accept these downsides, you basically have two options: accept it and go on like before, or find a job in a company that agrees with you.
Again, though you should let management take advantage of your expertise, you're not there to make the network run the way you think (and know) it should run, but to make it run the way they want.
Again, if "the way they want" is stupid (and it is), tell them, tell them again, and deal with their decision.
