I play around 1/2 of my games iron mode. It's my default way to play if I'm not explicitly trying silly suicidal things to see how badly they go, or if I'm not trying to optimize "puzzle fights" where reloading and doing it again (win or lose to try and win better) is the whole point.
Iron mode is nice both because it adds stakes and because it boosts the importance of game systems that, with reloading, rarely matter. Sensor profiles and gaming those for instance: in iron mode for the early game, the whole stealth game is very important and a whole lot of fun. Spoofing relays, firing off sensor pulses from asteroid fields, peeling off individual patrols, etc. Or looking at the bounty intel and actually optimizing ships for the fight.
That said, I don't think it should be default. At this point I've got a pretty good idea of how fights will go before I get into them, and I'm also good at realizing when a fight in progress is going bad before half my ships are dead. That's kind of an old fogey, playing forever kind of gut feel that new players just aren't going to have, and its an important part of playing just as aggressively as in standard mode without taking too many losses. I say "too many" because losing ships and gaining D mods doesn't actually matter up until it starts really cutting into the credit account.
For experienced players, I'd say give it a try and, on purpose, don't play more conservatively/cowardly. Go for the same fights as always. It's liberating to not care about losses and winning with no safety net is great.