[AngryData]

Ehh, the Hindenburg had a flammable skin. Barrage balloons from the World Wars were most often filled with hydrogen and yet were extremely difficult to ignite or take down even with purpose build incindiary ammo for that purpose shows hydrogen balloons can be safe. Often they would be riddled with dozens of holes but still take many hours for them to lose enough hydrogen to float back down to the ground.

The only real downsides are slow travel speed and vulnerability to extreme storms since there arent many places to put it with a large enough hanger even with days of warning beforehand.

[cyberax]

That's because regular bullets are actually pretty cold, especially by the time they reach the height of anti-air balloons.

But hydrogen itself is SCARY. It has an extremely wide range of ignitable concentrations, and it has very low ignition energy. It also tends to leak through ~everything.

[AngryData]

But hydrogen is also so easy to produce on demand that you can design your balloon to be at small positive pressure all the time and always leaks outwards into the open air. If oxygen is allowed to leaked in undetected, yeah that's a death trap. The same if hydrogen leaked into semi contained oxygen enclosures. But leaking through the skin of the balloon to open sky even with decent size holes and a bit of positive pressure doesn't ignite particularly well, despite hydrogen's wide range of ignition conditions.

It is not such a fool proof technology that everybody should have one, but to me building and operating a hydrogen balloon isn't dissimilar to running a steam locomotive. It can be dangerous if done badly or incorrectly, but it can also be done safely with pretty well known and understood technologies and methods and practices. And considering the massive efficiency of lighter-than-air transport I find it hard to dismiss its potential even so long after their heyday and previous problems.