They do have the Col de la Loze now, which can also be used as a pass. That's something.
And generally I feel like the ASO has actually tried to find new, or bring back old, really hard passes these last few years. The Grand Colombier has become somewhat of a regular Tour climb, they've introduced the Plauteau de Glieres and the Mont du Chat as their weak men's Mortirolos. It's just that they are lacking a real Mortirolo. If France had a climb like Punta Veleno or something similar, where all they would need would be some fresh tarmac and they would have themselves a new Tour icon, they probably wouldn't hesitate a second. But as it stands they have to build roads that are entirely new and who wants to make that sort of investment? Realistically there are bigger problems in the world than the Tour using a 15 km at 7% climb instead of a 20 km at 7.5% climb.
I also don't really agree that the hard climbs just aren't in the well paying regions. It's true that pretty much the entire French Alps south of the Col de Vars are underused but really those climbs aren't any harder than the ones in the north. It's mostly the Bonette and the Lombarda that I really wish we would see more often, but aside from that all those climbs are the same 10-15km at 7% monotony that we have throughout the entire French Alps and Pyrenees. And really while Bonette and Lombarda are cool, there are many climbs harder than those elswhere too.