I've been busy; sorry my response is a little slow but here it is.  To be clear, I am grumpy about this, not berserkly angry.
Re oldpilot and greg p I don't view the app a hobby nor do I view the app vendor as a charity.  That seems to be a bit of the flavor for you guys and I have no problem with it.  It's just not me.
Re Jeff Clark, the magazine subscription model is exactly what I was expecting when my subscription expired.  I accidently let my subscription to The Economist magazine expire a couple of years ago and, do you know what?  My last issue and the special issues were still all there by my reading chair and I could continue to use them for as long as I want.  Nobody from The Economist came to collect them and they did not self-destruct.
Shane, thank you for your usual reasoned response.  (Which is what I expected BTW.)  I think your arguments are a bit weak, except for the "everybody does it this way" one.  When I was beta testing for flightprep  IIRC that app didn't commit suicide when the chart deadlines came up, but that was another era.
Re charts I know full well that you get the charts for free and that I am paying for the georeferencing and other decorations. To nitpick that I am not actually buying the charts is a distinction without a difference.  Calling it a "service subscription" really doesn't reach takeoff speed either.  I don't need any more service from you once I have bought the charts with your value-added applied, so you have no argument that by continuing to use them I am not paying for something that I am getting. Call the product what you like, I still do not have access to something that I paid for.
Re expensive solutions not cutting users off because the solution was expensive, this begs the question:  What is the dollar point where it is "ethically wrong  for a company to stop functionality" ?  $10?  $100?  $500?  I don't think you can identify a bright line.
So I think, stripped down, your argument has two defendable elements:  (1) "We need to do it to keep our revenue up" and (2) "Everybody else does it too, so you really have no alternative."  So be it.
I still like the app.  I like the company.  I will almost certainly renew when the time comes when I need current charts, but in the mean time it looks like fltplan.com will meet my needs without there even being a subscription renewal issue.