Kinda what DG said, yeah.
Just because time flows 72x more slowly doesn't mean we won't then have the chance to abandon the seasonally-based arrival of the caravans. 72x more stuff can occur in a given year, so you'd be safer leaving the game unpaused so your dwarves can do their thing, and can make more designations while unpaused, and trouble may occur less often. Especially now that Toady intends to have the frequency of invasions switched over to some algorithm depending on the local political climate and distance to hostile entities; if you live right next door you'll get besieged early and often, but if you live some distance away, with many friendly settlements in-between, the goblins may be very rare. Caravan arrivals may work the opposite. It would mean succession games would need to change the way they choose how long to play, though, because few people can put in the 5-10 hours it takes to charge through a year right now in many succession games. At that point, instead of playing for a year, they just say "you have a week to get done as much as possible."
I think that if fortress mode were slowed down, there would be more time for other interesting things to occur in a given year, such as wandering traders and adventurers to show up, largely unannounced, and interact with your dwarves at the inn or markets you've developed. That also goes for hill dwarf and cavern sites around your fortress; there could constantly be some small population of merchants and citizens doing business, dwarves can have personal possessions (clothing and furniture in their houses) and private lives (producing goods to trade) in-between government (player) mandates, and a semi-capitalist economy, while you can still pop in at any time to tell your broker to go trade with them for this or that to add to your official horde. As it stands, dwarves don't live on a day-to-day basis, but rather take immense swathes of time to get your jobs done and thus there's little room to implement personal interactions in-between. Their "breaks" could be replaced by unpaid vacation where they go back to their personal lives, and they'd spend smaller and smaller fractions of the year eating, drinking, sleeping and partying. It could end up being far more efficient. Especially when you need to get the damn broker to go trade; the diplomatic caravans can still hang around for a month even if local merchants spend on average a day or two, but your broker won't spend that entire damn month goofing off; he only needs a couple hours to eat and drink at max every day, so even if sleep takes ~1/3 of the time there's still a large period in which they have nothing but their government-mandated labors to do.