That's not the same thing. Why are you comparing consumables with software? I don't care how much Tweetbot costs, if it does the job, I can pay $30, but I when I buy it, I must know the release policy of the publisher.
Is it going to be Microsoft Office where I have to pay for upgrades? Or is it going to be like Instapaper, a lifetime purchase? This is the point I tried to make.