Transaxle flush without changing the filter

This is a new one on me. I was at my ford dealership getting the oil changed (I've found disposing of used fluids to be too much of a pain in the ass in
my area, so I just let the dealer do it). The service guy tells me my trans fluid is due to be changed, they have one of the machines that flushes the whole system (100% fluid change).. So I ask him for a price quote, and he gives me 2 prices, one with changing the filter, one without. I asked him about it, and he said that it's not always necessary..
To me though, if you are changing the trans fluid, and not bothering to change the filter, it sort of defeats the purpose of the fluid swap, especially to save $40.. Am I wrong about this?
Oh, I have a 97 Taurus GL with ~115,000miles on it.
As a side note, is it worth going to synthetic fluid on this tranny? I know the Taurus transaxle doesn't have great lubrication, I'm just thinking longevity...
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