...Might as well keep churning out different versions of the same game if the demand is there but where does it end?

This part doesn't bother me at all. I will never buy anything "limited edition" (pinball or otherwise) unless it actually has some benefit that I personally feel justifies the price hike. For me being able to say "I have one and you don't" just doesn't cut it. I need to see something more substantial; whether it be something that adds significantly to the gameplay or simply something that I think looks way cooler.

Some people are prepared to pay huge sums of money to be able to say "I have one and you don't". It's these people who create the incentive for the manufacturers to keep pushing more and more models out until the reason they bought theirs doesn't exist anymore. Unfortunately the ones that lose out the most due to this are the people who bought the LE because they genuinely wanted all of the extra features for their own enjoyment but have to pay an inflated price because of the aforementioned buyers.

It'll get to a point like cars these days where 'limited edition' is actually dealer speak for 'left over parts that we've sprayed a different colour and slapped onto the vehicle at an inflated price and then added a XXX/500 sticker on to give you the illusion of owner something rare'.