LOL this stuff is hilarious.
I've been involved heavily with PP since I started Elite - well beyond the level of most of the folks going nuts over the proposed changes. I've suggested improvements, along with 99% of the active PP community. Open only was one of them. I'm glad to see FDev consider it.
I made many suggestions for the improvement of PP to my liking as well. PP missions were one of them. Glad FD listened to me.
Or.... maybe they didn't listen to me or you.
That's not how I envisage it'll be at all. The mere fact that a haulage run could be intercepted makes the trip more tense - the grindy feeling comes from uneventful trips and watching 'invisible' players move the numbers. Getting 600t of material to a given station would now have a deeper sense of worth and meaning, as opposed to 600t merely being 9% (or whatever) in the grind up to 100% fortification and then move to the next target. There will be real potential threats to prevent you completing a run; be that by destruction or forcing you to route. There is then all the cooperative gameplay elements to consider, from both attacker and defender.
It will be far, far from a grind as we know them now.
We will have to see how it goes then won't we, and just how much sense of accomplishment people really get from it