They gave up because they couldn't get it to look nice? If that's not the ultimate in form-over-function...
My cell phone, even my portable GPS have built-in calculators. Every PDA I've ever owned had one, right down to the two-line Sharp memo pad.
Too much space to fill? Just take a photo-realistic image of a calculator sitting on a wooden desk or something. That'll kill some of the space. Or make it an adding machine with a virtual tape. Or a TI-85 mockup with a huge screen. C'mon, they could have had a field day with this. How about a nice big scientific calculator? How about TWO calculators at once?
Weather? How can there be too much screen real estate for a weather app? Look at what the TV stations do, this could have been a huge opportunity for great looking graphics, mapping, trends, statistics...
Well, here's hoping the third party apps can fill in the gaps!