Once they get used to a good soft key board like you get on the iPhone or most Android phones people either don't want (or don't feel they need I suspect) physical keyboards.
I often hear people lament the design of their phone, caused by the preferences of the majority.
Making niche products doesn't work well for consumer electronics in general, unless you can sell that product at a much higher margin. Having a keyboard on a phone just doesn't seem to result in being able to sell it for twice as much.
Another issue with keyboards is they don't internationalize well. So rather than having 1 hardware design worldwide, you now either need a TON of SKUs - one for each country (and you can't move inventory from one market to another) or you need to further limit your target market to just a few regions.