Indeed, to me the issue is that too much is too random, they spawn too often and the content is too generic. In other words, you generally do not care.
DISTRESS SIGNAL RECEIVED should be a thrilling event. Currently you just shrug because you dont have a fuel collector limpet with you, and who cares about that NPC in his generic situation anyway. Make it rare. Pick it up across the system so you have to actually go somewhere. Have the survivor spawn chained missions for you, leading up to a big reward. I dont know, *something* more exciting than most USS we have now.
Ah yes, that's another issue though, aside from the spawning system of scenarios.
Many scenarios appear to be "unfinished" as in, they don't appear to have their own full contained narrative structure.
A start (not always needed, distress calls for instance, the start has happened already, though, there could still be it's own start, vis a specific message to you from the distressed, or the distressers, or a mixture of both.)
a Middle (this is in all scenarios, it's the STUFF you do in there)
An End, this isn't required in many (degraded emissions, your just grabbing stuff, the end is collecting the final piece, however, they have added an extra middle/end to these, via pirate traps, or other competing scavengers, this is a good example of doing something decently here!) however, in distress signals in particular, lack of a satisfying ending to these scenarios ruins the entire thing. You saved a guy! he is still calling out in distress.... huh, but your refueled! your not under attack anymore! surely I should be rewarded in some way...
And then, yes, the reward itself doesn't even have to be the end, it could, as you said, link, into other things.
Maybe, the guy on the ship, is just too damaged, and uses his escape pod, asking you to pick him up, becoming a passenger mission with specific parameters, and a specific reward.
Maybe, if you fail to save him, a black box is dropped, which another organisation then asks you to deliver, leading to more... I mean, Frontier I am sure, have these ideas, I just wish it was a priority for them to implement them!