Rule #1 of any hobby: Don’t tell other people how to have fun. 
Now, to address the merits, there are plenty of reasons people choose to buy some or all of their add-ons through the Marketplace, and this thread is not the place to debate them. With the recent change in policy from MS/Asobo to put the onus on testing and approval onto the 3rd party developers themselves, I expect the lag time for updates to drop considerably (as do the developers themselves).