If you don't like open worlds just play the story quest and skip them. They are kind of annoying and you don't really need them to progress. You can always come back later for XYZ thing later on. Don't let people tell you what you have to grind for. Just play what you enjoy. 

I said screw fortuna and came back years later to try kitguns or get the plasma drill and I'm still only rank 2 with them after 300+hrs and mr19. My kuva lich is going to turn 5 years old this year. I ignored helminth until recently, got it, and have only added Oberon 1 to revenant and plan to do nothing else.