I agree on security, but as a more practical point the market disrupters like Nest aren't thinking about reliability or the risks of DIY installation. I have to think Honeywell weighs that differently since they're not targeting the DIY crowd, at least initially.

For example, there were many incidents in January [1] where houses with Nest thermostats malfunctioned in the middle of a serious cold snap. One reason was that the batteries went dead in some thermostats, but normally the battery shouldn't be needed in normal operation when it's wired properly. Guess what, it wasn't wired properly by the homeowner. There should be a built-in diagnosis for that.

Another reason was that Nest sent a firmware update to thermostats in early January--in the middle of a cold winter? Where was their risk assessment on that? Maybe there's little risk of frozen pipes in Palo Alto, but it's a major risk in the eastern and midwestern USA.

[1] http://techcrunch.com/2014/01/06/nest-4-0-firmware-battery-p...