IOS has different apps and being able to say you have 500 twitter apps in a store had long since stopped being a benchmark. Of course if you're bough into the iOS or Google app ecosystem you're unlikely to changeto anything else without good reason.
W10 needs to bring more universal touch based apps to market without doubt, but many people have a laptop AND tablet which suggests there is a market for people who want touch style apps and full on Windows applications and games with mouse & Keyboard. Surface 3 potentially gives that in a single device. If you just want a Windows tablet there are plenty of other (cheaper) options and presumably more coming with Cherry Trail and Windows 10.
That's why it's x64 full Windows and not Windows 10 mobile or whatever it ends up being called. It's expensive as opposed to an Android tablet, yes, maybe, but as a replacement from me having to buy a laptop and iPad, then I could see it made sense as a student/consumer/non power user in a company etc. Not something for everyone, no, but a good premium option leaving room for MS OEM partners to produce cheaper, and more expensive alternate options.