Not intended in any way as a rebuttal of your point, but considering both sides of an issue is generally worthwhile:

There's the potential for DIY open source misuse, with negative consequences:

Here, a poster's bad experience with a properly-installed OEM product prompts a "warning", directed at the open-source DIY community...

https://community.particle.io/t/spark-powered-thermostats-bu...

The poster referenced this DIY...

http://blog.particle.io/2014/01/17/open-source-thermostat/?r...

I'm an open source fan, but realize it's not a panacea, in and of itself...great care and a full understanding of potential negative consequences is only prudent...

Personally, I'm content with nursing along older appliances that were made well...but, I'm a bit of a handyman, and hate to give up on any machine until I'm convinced it's totally worn out, so IoT is unlikely to invade my home on a large scale any time soon...