As a user I really don’t like to see an app I just bought now being offered at a lower price. I feel I made a bad decision buying the app. I regret the purchase. I also feel bad about buying an app I’ve already bought, just because I wish to run it on my iPad as well as my iPhone. Not only do I have to manage several versions of the same app, I have to pay for it again.
As a developer I really don’t want my users to feel the same way.
My thoughts exactly are the same for the new iOS App(s) I’m planning to work on – all are Universal and will run on all the devices. It is not worth wasting time building different apps for iPhone/iPad.