Hydrogen balloons are dangerous. I say this as someone who handles them relatively often. One blast can seriously damage your hearing if you are standing next to it. And they explode easily, too.
I was specifically talking about novelty balloons. Personally I think the danger is overblown in most situations, small rising pop (perhaps of flame), but if you have a problem with that, use air... with the goal of saving it for more important uses, like some of your examples. Blimps are another egregious waste, especially if usage scales up they need to be engineered for sustainable hydrogen.