I think there are two types of pinball players/collectors-those that see the games as a very expensive fancy toy that should be treated with care and deeply coddled. Then there are those that see the games as being built to be abused for years in bars and arcades, smacked, pushed and prodded to convince the ball to track nicely to the correct spot. The reality is that you can be in the latter group and will rarely if ever have an issue, and any issue you have is easily fixed. The other fact is you can be in the former and the same stuff mostly breaks.
Some people buy the latest truck from Ford and have the thing detailed and clay bar 3 times a year, others take it hunting and beat the crap out of them- they even get scratched! End of day, both drive down the road just fine.
Would it piss me off a bit if I really broke the glass, or if a friend did- a little. But I would clean it up and play on.
Nothing wrong with either use- just dont expect everyone to agree because there really are at least two ways of viewing these games. I personally view them as ruggidized beasts designed to extract cash, they can take an occasional smack in exchange for being quarter hungry.