I have the soldering iron that is based off, the TS100, and it's really useful. The CPU lets you regulate temperature, and it has features like lowering the temperature when you don't move it for a bit. That's what the CPU is there for, it's really just a microcontroller. Good luck making a (minimally decent) soldering iron without one for temperature control.
I think this is likely to be down to the different expectation/requirements of people who use their soldering iron a few times in 30 years, compared to people who have theirs hot most or every day.
I bet your soldering iron is fine for everything you want it to do. I also be it won't let you work with tiny SMD components or reattach micro usb connectors out at the drone field where you damaged it in a crash...
There are some cheap DC-powered soldering irons in a similar form factor which use a dial and potentiometer to set the temperature and an op-amp for temperature regulation. No processor in sight. Apparently they work reasonably well.
Does it give you a digital display of the temperature (in Celsius or Fahrenheit, configurable)? Does it sleep if not moved? Can it run off a battery pack and monitor the power of said battery pack to safely shut off?
Not everyone needs those features. If you do or want them, the moment you add even the simplest logic, you are better off getting a microcontroller already. No reason to bother with discrete logic chips anymore.
I have used for many years a standard soldering iron (not even a soldering station) with zero logic whatsoever. It worked, but nowadays I prefer to be able to set the exact temperature I want, to the degree. And to be able to monitor if the iron is able to handle the thermal mass I'm trying to solder.
Desktop soldering irons have had sleep features for years -- the temperature relaxes when you put it in the holder (or after it's been in the holder for a while) to reduce tip oxidation, but keep it warm-ish so it'll be back to soldering temperature very quickly when you pick it back up. These are based on a processor, you just don't have access to it as a user, so the timeout and temperature are set by the factory and that's it.
There are plenty of soldering irons with a digital display, which allows you to calibrate the temperature response using a simple two-point process, rather than back-and-forth twiddling of the gains of a couple of opamps on the old analog stations. Those were such a pain to calibrate, few folks bothered, and the temperature setpoint on the dial grew increasingly fictional with age. The digital ones are based on a processor, but often the UI is so terrible (two buttons, three digits of 7-segment display) there could be more features back there but nobody would use them.
When OLED displays got cheap, that changed things. You can now have high-res text without a huge screen, and finally give someone all the knobs they'd want. Timeouts extend tip life. Calibration is really good and easy. Momentary boost mode for large joints without having to change the setpoint. It's the features you'd find in a thousand-dollar Pace station, in a sub-hundred-dollar portable iron, because all the complexity is in software.
And, bonus, since it runs off random DC, you can use any laptop brick you have sitting around, or batteries. They're extremely popular with RC hobbyists for field repairs as a result, and when running from battery you need another feature -- low-input shutdown, so you don't accidentally overdischarge the battery, which can damage it. Yet another feature that costs $0 once the hardware is there.
I like that it's small and I can just plug it to USB-C charger that's on my table. I also have a bigger soldering station, but it takes valuable space on the table.
For quick soldering jobs it's faster to just use pinecil, instead of setting up soldering station on the table.
I don't care much for electronic control. Apparently it has a bunch of features, but I don't use any of those.
Lower the temperature or turn off when not moved for some time, better temperature control via PIDs, set a voltage cutoff when running off battery packs...