My guess is it allows them to build a lighter and maybe stronger action with a change in manufacturing techniques?
I agree.
Browning didn't use hard steel inserts for the heck of it.
It is one reason the bolt slides in and out like it is on greased rails.
As for Frank Barnes quotes you linked too.
Mr. Barnes was perhaps one of the best students of bolt-action & single shot rifle actions to come down the pike and, write books about them.
But he was also very old school.
If it wasn't built like a fine 98 Mauser, or Mr. Barnes idea of a possible improvement, it was just wrong!
In todays competitive rifle market there are two schools of thought.
You do what you do to either make and sell a rifle as cheaply as possible.
Or make it the best you know how to make it in the price range of the market you are in, and charge the going rate.
Browning follows the second school.
If you don't like hard steel inserts, you could trade it for a Remington 710.
They use plastic inserts!
As for replacing the barrel?
How soon do you plan to need a new barrel?
That much ammo will cost you way more then you paid for the rifle.
So you can probably afford to send it back to Browning for a new barrel when & if it ever needs one.
rc