Starmaker: I suspect this might be not strong enough. It is quite possible that unlocking perks and changing the loadout is the intended way to progress through the story missions, and the average player is not expected to succeed at some of them with the default loadout and thus will not be able to "complete" the story either.
mrkgnao: Thank you. Added a few more words.
No not really, you can complete the game easily without any unlockable. Also something that some peoples seems to mistake is that default loadout doesn't mean it's the "only" loadout and that you won't be able to use anything else.
It only impact what you are starting with, you can still get plenty of weapons, disguise, and gadget in the map itself, also the game is not very hard, it's a lot easier than most of the old ones, you can easily get detected kill half the map gun blazing and still survive and complete the mission. Heck I remember watching video of peoples killing everybody on some map using only a frying pan.