I love my Nest thermostat. We bought one of the original versions when they were still a relatively new thing. This was back when the company was still a scrappy little startup run by Tony Fadell--who also happens to be known as the "father of the iPod."

That actually tells you everything you need to know about why the Nest was great--it was beautifully designed, but even more important, it was simple to use. Oh, and it was smart.

Then, yesterday I got this email, and it's a perfect reminder of why people haven't been exactly thrilled to watch their favorite smart home brand die.

First, a brief history.

Back in 2014, Nest was acquired by Google. Let's just say that loyal Nest-fans weren't particularly happy about the idea of their favorite smart-home device becoming a part of the world's largest collector of personal information.

There were fears of Nest thermostats being used to feed data into Google's ad-driven, information-craving, privacy monetization machinery. At the time, users were assured that Nest would remain an independent company and continue to develop products on its own.

Then, last year, Google merged Nest into its own hardware development team. The move was supposedly intended to help strengthen Google's own hardware chops, but again, the writing seemed on the wall that the beloved Nest family of products was moving closer to becoming a part of everything they were afraid of.

Just last month, Google announced that it was essentially retiring the Nest product line and brand, and integrating all existing products into the Google Home ecosystem. Instead, Google would treat "Nest" as its sub-brand for all of the company's smart home devices. Google Home and Nest became "Google Nest," in the same way that the company's smartphones are the Google Pixel family.

The end of Nest was finally here.

Now, in confirmation of everything Nest fans hoped would never happen, Nest became a full-blown part of Google. That data-privacy barrier between your smart home device and Google is gone.

Look, I use Google products every day (except Chrome). I have a Chromecast at home. I use Gmail, Google Maps, and even a Google Pixel 3a as a test device. Still, I never intended Nest to have my information so that anyone could market Google products to me.

When I gave my email address to Nest to set up my account, it was so that Nest could tell me about important things related to that service. It wasn't so that Google could use that information to sell me a phone. I'm sure that technically, I agreed somewhere along the line to some terms and conditions that gives Google permission. That doesn't mean that it's not a terrible idea.

Crossing a line.

People who bought into Nest, especially early adopters, weren't buying into Google. In fact, I suspect that there are plenty of them that don't pay attention to happenings in the tech industry, and basically had no idea that the thermostat they bought was made by a company that no longer exists because it's own by Google.

My wife is pretty smart, but when I asked her, she didn't know. Mostly because it didn't matter to our daily life. Our Nest just works like it always had.

Except now Google is trying to sell me things in my inbox under the banner of Nest, to my email address used by Nest to send me energy-savings updates. Using that info to send me an offer on Google Pixel phones is such a "Google-y" thing to do, and that's exactly what's wrong.

By the way, there will probably come a time when your business has an opportunity to do something similar. You probably won't buy a smart home brand and integrate it into your business, but that doesn't mean that the chance won't come along for your small business to make the same kind of marketing mistake.