Yeah, it wasn't a major complaint of mine, it was just very contrived. But like I said, it's done differently enough in each region, and in one in particular there is a very good explanation for it that was probably the high point for the entire game plot-wise, so I just accepted it.
Anyhow, my campaign took about 30 hours but I could easily have done 50+, there is so much fucking shit to do in this game. As you noted, the Resistance Points setup was nice. You can go back and keep playing after you beat the game which is nice, too. I'll probably wait for the DLC to play again, to be honest, because 30 hours is a lot for me in one game and I have tons of others to get to. The DLC content looks very cool for FC5 though.
I also found the Guns For Hire system to be a really nice change for the series. The Specialists all brought something unique to the table and I ended up having one with me for the majority of missions/outposts, and they never once really hindered me or annoyed me in any way. In some cases, they were crucial.
I just really love this series, and I get that it isn't for everyone. I'm already wondering what setting they will choose for the next game. Tonally, these games are indeed all over the place and story is definitely their weak point. Yet somehow they manage to get me invested every time. I don't play a lot of FPS anymore for reasons you specifically stated- it's gotten stale. For some reason, I keep coming back to Far Cry. It's just pure unadulterated fun, and we can spend hours breaking down the "message" the developers want to convey with this series, if any, because there are a lot of interpretations out there (spent an hour reading others' thoughts on the endings, and no shock at all it was pretty polarizing). Especially after the batshit insane ending(s) of FC5. But at the end of the day as a video game, I had a blast.
High hopes that the Vietnam DLC includes some fucking bladed melee weapons, though.