Earlier quoted context omitted.
If the place is packed you should raise prices.
Not really. Their goal shouldn't be to maximize profit and they should take care not to price people out from access to cultural artifacts. If the goal is just to reduce the number of visitors then a lottery system or limitations on ticket sales issued on a first come first served basis is far more fair.
The problem with cases like Mona Lisa is that Louvre never really is that overcrowded, but Mona Lisa attracts a crowd at all times (even if it's less than 1% of all visitors on the grounds of Louvre, that's still a lot).