In our GNU-Linux world Network Manager became the default solution in the vast majority of distribution
I guess this choice is mainly due to the lack of alternatives.
Network manger may have a nice design but it deamons is absolutely terrible and since system.d imposed itself it is more buggy than ever
As we all know we have to turn it off to be able to pass properly monitor mode with airmon-ng (with check kill )
That's very annoying
If we dig a little we will see that netwrok manger
- doesn't allow to change mac to connect to an access point
- doesn't let ifconfig switch on or off an interface
- in kali 2016.1 (specific and very annoying bug) it simply doesn't allow you to use a single wifi interface if you use two. Or boithes are switched off or bothes are switched on
To say it simply, network manger doesn't let the user to have a control on its interfaces.

If these features may not interest a regular user of ubuntu or linux mint, it is not the case for a pentester...
...Not so far ago wicd was the default network aplication in backtrack

The wicd project is maybe less famous and may look a bit "abandoned" as iut has a new version every two year
But it is stable, reliable and absolutly conflictless with other command line tool

Some may argue that it is less fancy and trendy then gome netwrok manager...
But should that be a priority in pentest distribution? (that a rhetoric question in case you didn't get it )
wicd is a python open source code and its design can be simply adapted (gtk) to kali linux look

I really wonder how network manger could have been choosen by kali team and how can't this big lack of functionalism hasn't been detected (and that's nothing new)
I wonder why "at least", if kali staff want to stick to network manger, why they did not automatize playing with netwrok manger conf file to exclude the interface that we want to use in monitor mode or whatever.
They are several themes in this forum and others about this isues and tips to solve it... the simplest one is without any doubt switching to wicd

My aim is not to criticize but to help kali linux to improve. My feeling is that there is a gap between the comunity and the staff, this forum should help to create bridges and should be a place of exchange but we barely - never - see any kali developer answering or explaining stuff...
Is that's really how a GNU-Linux distribution should work? (that's also a rhetoric question)

Yes, there is the " bugtrack "... but that not the place or the form to generate dialogue and exchange points of view.
I think this forum lack of partition from developer, that the community is not listened too and that leads to very bad choice like having network manager as a default network manager