Iron man and self-imposed iron man type runs are there for the people who like prefer consequence and surprise over progression. It is not inherently better or worse than any other play style, given at the end of the day all that matters is whether you had fun playing or not.
I did find spacer start iron man runs made me engage with more of the mechanics in the game I tended to mostly ignore before. I found myself using sensor/stealth mechanics. Less being lazy leaving my transponder on in hyperspace. Really considering all the pros and cons of various ship and skill choices. Sensor skills are more valuable in an iron man run since they give you more reaction time. In a world where you can reload, you can always have the options of knowing what is in the immediate future with zero "risk".
As for fleet composition choices, a Hammerhead is stronger in a straight up fight, but Shrikes have burn 10 and run away much better when a surprise capital fleet suddenly appears out a hyperspace storm. Buffalos are probably the king of efficient early game cargo capacity, but a properly built Cerberus on retreat is essentially impossible to catch (185 base + 50 SO flux boost + burn drive hits 435 - this thing is almost as fast as thunders when burning).
I don't know if that's a "cautious" or "passive" play style, but it is a different play style than what most would probably consider a normal play through. And depending on how you view the game, you don't necessarily need to play more cautiously. If you're more interested in progression, really powerful or unique end game ships, then I can see that view making sense. If you view the game as a series of missions that simply have some continuity, then each fight can be viewed as standing alone, interesting in and of itself despite what ships you might have. At which point, it doesn't matter if you wipe and get sent back to a frigate somewhere in the core. Which actually isn't even that common of an occurrence given the retreat options built into the game. Assuming one is willing to retreat.
Although, I admit having a high level character with a full skill tree and a bunch of hull mods unlocked with a single frigate is actually a very different play experience than starting normally. I may have ended in that situation once or twice.
Due to iron man, I've fought and dealt with situations which I might not have otherwise. In one game, I've literally used a single Shrike to distract multiple raid fleets in hyperspace while my colony finished building its defense station, then went back and grabbed the rest of my rag tag fleet to defend it once completed. I led them around, and occasionally engaged if they started to head for the jump point. The retreat scenarios I engaged in actually ended with a few dead frigates, the larger ships far behind, and a surviving Shrike. That is certainly not a typical combat scenario I'm guessing most people have tried. I found it interesting and different from, say, another Atlas Mk II capital grind late game.