Admittedly .aero and .museum have less than 10 thousand registrations between them, the question will be whether they can survive financially at that level. If we are to believe Gilmore's figures, it doesn't cost a registry very much per name. And I do know one thing. As a hobby which became a sideline I sell rare books online. If I had to pay say $100 per year for a .book or .books domain, knowing that consumers would only find books there, and would be much less likely to have to wade through drek, I would consider it money well spent. I am not suggesting that any and all new TLDs, open or restricted (and we almost certainly won't see any of the former for many years), would have to charge this price, only that I don't see it as out of line for commercial use. A yearly yellow pages display ad can cost many times that. I also see no reason why the same registry could not handle more than one TLD (VeriSign has managed to do so), allowing economies of scale, and a commercial TLD could be priced higher than a non-commercial TLD.

On your second point, I am ambivalent about ICANN attempting to become, amongst other things, a consumer protection association. OT1H, I can see the merits in what Tucows has to say, and generally find them the sanest voice in the registrar community. OTOH this could, and given ICANN's record to date, probably would, lead to more mission creep, and from the same record, they could well handle it badly. I do find it absurd that ICANN will accredit registrars with next to zero oversight other than whether the applicant can afford to pay ICANN, while putting registry applicants under a micro-manage microscope. -g