There are rounded N95 masks, too. The important part is probably the behind-the-head straps.
The greater force means a better seal. But that seal comes from your face deforming to fit a rigid mask, and your face would prefer not to be deformed.
It’s better to use soft polyurethane or foam to seal around the edges, and that’s what some P100 masks do. But because they have higher upfront costs, they have cultural associations with industrial work and gas masks, while people use disposable N95s for things like woodworking. Also, the typical design with 2 flat filters to the sides makes it harder to talk to people while wearing them than disposable N95s do.
Here is a typical disposable P100 mask. It adds a foam seal around the rim, and it’s much more expensive than a N95 mask. I doubt the production cost is that much higher, and in theory, the foam seal could be separate from a replaceable filter.
I understand why MIRI has Yudkowsky, Bourgon, and Soares as “spokespeople” but I don’t think they’re good choices for all types of communications. You should look at popular science communicators such as Neil deGrasse Tyson or Malcolm Gladwell or popular TED talk presenters to see what kind of spokespeople appeal to regular people. I think it would be good to have someone more like that, but, you know...smarter and not wrong as often.
When I look at popular media, the person whose concerns about AI risks are cited most often is probably Geoffrey Hinton.