You need to stop trying to apply this flawed logic that adding missions to free flight will somehow gut career mode. Doing this will take nothing away from career mode and will ADD something to the game that some (maybe a lot) of people will obviously enjoy.
The only reasonable downside that has been put forward in this thread is that if missions are added to free flight then no one will want to play career mode and MS will starve it of resources. I don’t believe this for one second. There are three groups of players.
1.Those who like career mode and will play it no matter what.
2.Those who hate career mode and will never play it - some of these might be interested in missions if they were not gated.
3.Those who hate career mode but will play it, grinding their teeth the whole time just to get access to the missions which is what they really want to do.
It is my considered opinion that groups 1. and 2. are both a lot bigger than you think and group 3. is not really big enough to have much of an effect.
TLDR: There is little to no down side in adding missions to free flight and potentially a very large up side.
P.S. The elephant in the room (see what I did there ;)) is the worrying possibility that MS is really trying to turn the sim into a true MMORPG, complete with micro transactions and pay to bypass grind. Should this prove to be true in the long run then you will get your wish and I will probably hand in my wings for good…