I would think that simple devices are easier to secure. They don't have the same horsepower available for encryption/decryption, but they have far fewer vulnerable spots than a complex system. I doubt that anyone knows how many points and methods of potential entry there are for a typical PC.
A blue tooth device may have only one point of entry and only one protocol to defend. If the 8-bit MCUs don't have enough power to be secure, even at that level, maybe the low-cost 32 bits will be able to make greater inroads by meeting that requirement.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.