Re: “unlike tablets, Kindle is designed just for reading”
Uses a different technology.
Cheaper to produce.
Better at being a reader.
Less expensive than a Tablet (by a large margin.. and don't go quoting your Cell provider's price unless you include the contract markup)
It isn't a tablet with limited capabilities. It is a completely different item all together. It is also MUCH better at being a reader than a tablet is.
I get what you're saying, but it doesn't really apply. It is a purpose-built "tool" with a specific function.
Should we all buy Semi trucks instead of cars? I mean... they can haul more.. so better yes? Or how about motorcycles? We could fill more parking if everyone rode one instead of a car.
If you need the extra functions, buy the device which meets your needs. If you want something specific for digital books, a Kindle (not Kindle Fire) is an appropriate option.