So, your point is light and more rigid materials. You haven't answered sjbe's point of slow, bulky, and cannot fly in inclement weather. No matter how light you make your airframe, an airship is always going to be bulky because of how buoyancy works; to float, it must be lighter than an equal volume of the surrounding fluid. But being less weight is awful in view of winds and storms, and being bulky sucks for achieving any appreciable speed.
So, at best, you're offering the public a mode of transport that is slower than airplanes, takes up more room at an airport, and flights must be canceled if wind gusts along the route get too high, winds that a 777 can punch through with barely a bump. And yet still your airship must slurp tons of fuel to fight wind-resistance and air currents. Who's gonna buy a ticket for that? You wanna get somewhere, you're better off walking or taking a bus.
The nail in the coffin is the lighter-than-air substance. Hydrogen? Expensive and burns, see Hindenburg. Helium? Expensive, planet Earth is running out of the stuff, and retrieving what there is often comes as a byproduct of dirty fossil fuel drilling. And they both leak like mad from whatever container you put it in, especially something lightweight for floating, consequence of being such tiny atoms. Worse, you got to bleed even more of it right out into the atmosphere in order to land. Lighter, more rigid materials don't do shit for this. Dirigibles suck. Own it.