A very wide generalization (which means take this with a grain of salt). I've worked in some part of the network security side of things for almost 25 years. The idea of connecting anything to the internet that doesn't need to be connected to function is just right out silly. This goes for locks, appliances, thermostats, cars, and often even computers.
A basic premise of security is: least privilege. I.e: always use the least amount of privilege needed for a particular task.
A basic premise of hacking is: pivot mercilessly. In other words: more often than not one exploit can be used to pivot and lead to another. I suspect most home automation will make awesome pivot points.
Regular old keyed hardware locks are hackable. But these are known hacks... and require physical access. (Hell, you can also throw a brick through the window). But giving someone the ability to open your door from Bangladesh ... that's crazy.
