Alyssa is I believe a gateway character. Antonio is the first dick she's had since getting married after all. So her and Sophia will likely have more fun with toys, it just depends on whether L&P considers that to be a sex scene. And since you need to be accepting Aiden's tasks in order to get her scenes, she's likely a transition to any eventual Sophia/Dylan down the road. Aiden too. His storyline is to get Sophia depraved and corrupted enough to sleep with Dylan, even if they themselves never get to. The Morello brothers, we've yet to see how useful they'll be.
Nathalie, she's the GW threesome option, as I've said numerous times today.
The Bennett storyline, I think that was a storyline that L&P tried, but found to be unpopular, much like what I believe was L&P's original idea of having Liam as a second MC. L&P discovering Dylan becoming a popular character might have had something to do with it turning out Bennett was treating Dylan unfairly in the test. Just speculating on that though.
As for the side jobs, yeah, I don't see their point. They might have had one back when events had Filthy point requirements, but now, not so much.