I think the small marketshare is a more agreeable reason that the different screen ratios. If a developer can't be bother to make a "two-line config change" then surely s/he wouldn't have targeted the iPad even if it had the same screen ratio.
I don't believe that Steve Job's godhood, nor the Rapture sparked by the iPhone App Store, would have prevented some developers from taking advantage of an iPad with a similar screen ratio to pass off upscaled iPhone apps. However in addition to the carrot of robust iPad development tools, Apple was also wielding the stick of restricted access to the App Store. Don't forget that the period between the iPad's announcement and release was nadir in iOS censorship where Apple banned cross platform development tools. I'm sure Apple could have provided sufficient discouragement to developers if the iPad been the same screen ratio.
P.S. The lack of an iPad Facebook app is a poor example, in my opinion, as I'm guessing that the development cost is something Facebook could easily afford. I believe Facebook would probably not rather an iPad app encroach on the website usage and inadvertently end up ceding control of ads and analytics compilation to Apple.
Those are some interesting observations about the Windows Tablet PC. I initially assumed they've always received bad reviews simply because the core product wasn't any good but I've recently been surprised to discover passionate adherents of the OneNote app for tablet pcs (while reading up on the One Note app released for the iPhone). Makes one wonder why none of the iPad's new competitors have incorporated a stylus...
And yes, I would like you to stick the Cydia iPad disclaimer right next to the iOS 4.2 warning instead of taking up half the screen ;). I am glad though to see some of the innovations from the Rockapp finally seeping into Cydia.