If you are the one that has to pay for, maintain and fix any issues caused by kids playing your machines then you should be concerned about it. Most parents will curb their kids, but if that adult is playing another game they cannot supervise their kids. Nevermind, "the machine can take it". If you have to fix it, then by all means enforce it. I have an arcade sign that says "Please respect the equipment and most of all have fun". This is there for adults, have not seen one kid actually read it.

I looked over once and my 2 yr old daughter had pulled all of the Super Chexx rods out on one side of the game and was hanging on the rods like it was a jungle gym. I decided that even though Dad could, the machine "could not take it".