To the question of "pressed penny machines" being appropriate for a museum,
it is, perhaps, a question of "taste," as Christopher Dill suggests.  Yes,
they provide a bit of income for those businesses that offer them.
Personally, I associate them with tourist traps, county fairs,
Crackerbarrel Restaurants, and other places catering to souvenir-seekers.

If mangling a coin is regarded as an educational experience that a museum
wants to offer, fine.  If, for 50 cents a youngster can activate some
interesting and informative whiz-bang on a computer that "extends" the
museum's educational purposes, that'd be my choice.

And as ReidArden writes, it's more fun to put the penny on a railroad
track:


I've seen these before, and have never understood it at all. I think there
is
one at the local zoo and I always think "why?". Maybe at a treasury museum
or
something....
Besides its so much more exciting to lay a penny on the train tracks.
Trains
are, in general, cool, the ground rumbles, and you don't loose 50 cents.
(Disclaimer: I in no way promote or condone placing pennies on railway
tracks,
its very dangerous and I'm sure it's covered under the domestic terrorism
bill
;-)
Reid