It's not even just that. It's two major watchOS releases behind. Likely dozens of severe vulnerabilities have been found in watchOS since the first-gen watch was last updated. Not just in the app frameworks, but kernel vulnerabilities and Bluetooth/Wi-Fi vulnerabilities. Simply being in proximity to a public venue where a malicious actor is present might be enough to be compromised.Anyone else still riding a horse and buggy? It rides fine and gets me where I'm going. I'm saving on gasoline, while all you losers rely on big oil.
Not to mention, the first gen doesn't have a Secure Enclave. I find it hard to believe that the battery has held up fine after years of daily use, as my first gen barely lasted a day when it was new. It often hit 20% or less in the early evening by the time it was 2.5 years old, and had to get a top-up on the charger to make it through a full day.
Having had an S4, I'd never go back to the first gen. Grabbing a used S2 or an S3 on sale is a better choice in 2020, if price is the issue. The performance of the first gen was so terrible that some apps like Messages are so slow that they aren't practically usable. They technically "work." But waiting 20 seconds for the app to load into memory to send a quick "OK" isn't worth it. The convenience is completely mitigated by the performance of the watch. I'll just pull out my phone and be done with it. The newer models make those apps usable simply by being tolerably faster.
The first Apple Watch was the like original 2G iPhone. It broke a lot of ground, but it was quickly obsoleted by better, faster hardware that is far more capable and future-proof.