At least in CentOS and RHEL 7, NetworkManager does VLANs and Bonding and bridges in about 2 clicks. Add interface, choose bonding | VLAN | bridge, and go.
bridged VLAN's (yes, those are a thing)
Set up your VLAN interfaces, bridge them. Not seeing the issue.
And ... and... well, 90% of the other functionality that is offered by the Linux networking stack.
90% of the other functionality isnt relevant 90% of the time. The point of a GUI is to offer the most common options, and from my usage of NM, it does that admirably.
So sure, if you're a sandwich shop putting a $500 server under the cash register, or you are a teenage college student setting up a video sharing network for your bro's in the flop house you board in, NetworkManager will work fine for you.
What about a network engineer who has better things to do than spend more time researching the syntax for setting up tagging on a single node than it took to set up the switch infrastructure?