It seems inevitable that ease of use and security are inversely proportional. If you want ease of use then security will be bad and if you want security then it will be a PITA.
No it isn't. It just costs more because :
It's hard to make something usable by average Joe, that's why there are UX designers and they make their living from it.
It's hard to make something secure because networks are very complex and require a lot of knowledge.
You have every tool that you need.
You have company servers which can distribute fw updates, certificates or whatever.
You have a powerfull device with internet, bluetooth, wifi and USB.
You have a device wich can connect and host wifi, bluetooth, USB.
If your implementation sucks in security or usability its your fault.
The problem is that it's not as easy as an arduino board, write code 2 days and sell it. Some things requires development time and knowledge.
And it's a lot easier when you don't reinvent the wheel on things that you are not an expert of because possible issues are already solved by others.
Also you have to understand what your audience finds "hard". You may find easy to connect with it with a terminal, don't assume that this is usable by others!
As already said you can read about UX design to find what is the most user friendly method now. (Accelerometer and vibration motor are not high in list...)
*PS routers don't spam you about updates because they want to be performed by people who have basic knowledge about it and can comunicate in case of something goes wrong.
They are not stupid, they just don't wont to spend money to make it idiotproof.