Oddly enough I'm surprised that a painted stem would corrode to the point of seizing. I'd almost place my bets on the stem being slightly oversized, and "persuaded" into the steering tube.
I'm with Terry here, consumer designs that are more forgiving to neglect are better, all other things equal. For one thing, neglect could start at the factory. Does it mean getting rid of the old stuff, or merely treating it with the knowledge and respect for its failure modes? That's an individual judgment call. I'm willing to keep some old bikes despite needing a bit of TLC and care in reassembly, not others. I grease everything.