I have to point out, as a professional writer and editor, that learning to write properly in the first place avoids the issue by making it impossible for you not to capitalise the beginning of a sentence. It's been my experience as a teacher and coach that people who don't capitalise by habit tend to take other "shortcuts" in their writing ... like relying on auto-correct to fix their spelling, etc.
As for Pages, MacInWin has it pretty much correct except for one thing: it's not premature, its quite deliberate. We've seen this over and over and over and over with Apple: periodically they will tear down an established "structure" and rebuild. Over time it surpasses the original in every way, but it takes time. I'm not a huge fan of it either, but it beats waiting 5+ years for a perfect version to come out. Apple felt they had covered the basics but apparently overlooked a couple of things (mentioned above) that are really necessary. Should be fixed soon enough, but here's a hint: when they deliberately leave the old version around and don't replace it outright, that means they are already well aware that the new rewrite is missing features that will be put back in later. That's why they leave the previous one there, so the power users can keep right on using it.
I've been teaching Pages to a bunch of new Mac users who have never worked with Pages before; they only know Word. So far they are ASTOUNDED at how much better Pages is for their purposes. I resist the temptation to tell them that if they like this Pages, they'd have loved the previous one. But to them it is very fresh, clean, and does everything they want it to do simply. They would not ever think of not capping a sentence and expecting the machine to do it for them (these are retired teachers, mostly!), so they don't notice stuff like that at all.
