>> If you afford a bluetooth chip you can definitely definitely afford a CPU that can push 2-5mb HTML files through it in reasonable time
Maybe not. I'm using a micro controller with specific peripherals and ADC requirements for a high speed control system. This has less RAM and flash that you can probably get away with for a web server. We'd have to add a bluetooth radio chip, but I hear those go for well under $1. There are all kinds of embedded devices that have few resources but could be expanded with cheap Bluetooth connectivity. I realize this is changing quickly, but there will always be very small devices.
Yes running a full blown web server with HTTP support requires a bigger CPU and RAM, but don't need a lot of RAM or CPU to stream an HTLM file through blutooth from flash storage. Serving data over blutooth for that HTML application would need some custom stuff (because it would go over blutooth and JSON-encoding for messages would probably require too many resources). My point is that it is definitely possible to serve a HTML file over blutooth, render it in a app through an WebView and have the app communicate to the device over blutooth without putting a beefy CPU in there.
The product I worked on the bluetooth chip was more expensive than the CPU if memory serves me right and we did something similar. But I am not a board designer or procurement expert.