I'm not convinced the security is notably better.
Ha, not surprised you don't believe security is better. Security is on the level of iOS or Android, everything is sandboxed. ( https://support.google.com/chromebook/answer/3438631?hl=en ) And updates are as smooth and unobtrusive as they are on iOS or Android; don't get me started about problems with Windows updates.
Really, it's not bad. It's surprisingly really good. Of course, if it weren't for Crostini/Linux it would be too limited for many people to use as their main computer. But with Crostini, it's pretty great for the right users. Pixelbook hardware in particular has a quality feel, makes you feel good just to use it. And the software has a polished feel, too. It just works. Windows, in comparison, feels like a clunky mess; a complex, clunky, mess.
I got the Pixelbook on sort of a lark, on sale for $699 back in November 2018. The hardware is 8GB, Core i5 processor, 128GB ssd, 2.4 pounds, beautiful 2400x1600 (that's 3 by 2) touch-screen display, high quality construction, excellent keyboard and trackpad. 10 hours battery life. And fanless. (Also 2-in-1 form factor, flips around for use as tablet.) I didn't expect it to become my main computer, but it has.
Complex? Well, I don't know about that, but they do say the mark of a good product is that it makes complex things seem simple. Or something like that. That's what I'd say, anyway, about the Pixelbook. Best machine I've ever owned. I'd rather be running full Linux with i3 window manager, but it's not worth switching (and giving up instant boot and higher security of Chromeos).
I don't think I'd recommend Pixelbook/Crostini if you're heavily into x-window apps on Linux. I rarely use them; I'm mostly just on the console/terminal and it works well. I've tried Firefox in Crostini, works fine, but it's not as snappy as Chrome.
RE: Google. I'm not a fan of Google, so have to get past that when liking the Pixelbook. And it seems Google is not very good at supporting their hardware. Fortunately, I haven't had anything go wrong. At some point I will want to upgrade to a more powerful machine, I expect. Light weight (the closer to 2 lbs the better), good battery life, and fanless operation are important to me, and I'm not sure there's any machine out there that I'd pick over the Pixelbook right now. At least not for a reasonable cost. Pretty amazing given that Pixelbook came out in 2017 and I paid only $699 for it.