Again your facts are completely wrong. There are a few Samsung Galaxy S2 models with a Snapdragon S3 (please use the proper names because if you keep using S3 and S2 all the time this is going to be very confusing), but those models never got an update to Android 4.2. The only Galaxy S2's that got updated beyond Android 4.1 are the Exynos models. And what is an "official custom ROM" anyway?? That makes no sense, if it were official, it wouldn't be custom. I think this is a case where a developer added the word "official" to the name of the ROM to make it sound fancy. Looking through the I9100G forum (a Galaxy S2 with TI OMAP SoC), there's an "official" entry for MokeeOS with a Linux 3.0 kernel. As I will point out next, we are actually better off.
About the kernel, we have a Linux 3.4 kernel so that makes your last bit a bit redundant. I think you don't realize just how good we have it, our Linux 3.4 kernel is really good, and Sony didn't have to update it for us but they did and thanks to that we now have great KitKat custom ROMs. The Galaxy S2 with Exynos is the one gem out there, all other phones from the last year never got that kind of treatment. It's unfair to point to that one model from the biggest player in this business and saying that all other smaller companies should behave exactly the same on all their models. Samsung doesn't do this either (oh and the Galaxy S2 got updated to Android 4.2, not 4.3). So just stop pointing to other devices because ours got treated pretty good, we have a good kernel and stable custom ROMs. If you have issues with the custom ROMs like random reboots, you're doing something wrong.
The Xperia S might have been Sony's "flagship" device at the time it appeared, but it was hardly high-end. It ran Gingerbread, the SoC was a year old. Only the screen could be considered above average but it's actually a burden for the lower end GPU. This was all reflected in the price, I don't know about you guys but I didn't pay a lot for this device. If this was a €500+ phone I might agree that more updates were in order, but the price dropped very quickly. I also want to point out that that "flagship" argument makes no sense at all. Imagine a Chinese manufacturer making a line of smartphones, do you expect the "flagship" of that line to be updated as well? How do you even quantify what a flagship is? Sony released the Xperia T in the same year as the Xperia S, doesn't it make that one the actual flagship?
You pay for updates along with the price of your device. If you get the cheapest iPhone, you know that it isn't going to get the next version of iOS (and I paid less for my XS than I'd have to pay for an iPhone 4S at the moment). The only reason Nexus phones get updates faster and the devices are cheaper is because Google has a completely different business model. As long as you buy your phone from a company that completely focuses on hardware, you need to continue buying hardware.
Also, that update to ICS completely counts as an update, it was sold with GB and the ICS update took months to appear. If we were to get an official Android 4.2 update, it would probably not be ready even now at Sony's pace. It's just naive to believe that Sony would change their habits just for us.
This is an issue that will always remain in the current system of smartphones. What we need for this to change is modular devices. Until then, you'd better stop moaning about these updates because you're just making yourself sick and nothing is going to happen. Learn from your own mistakes, there's no need to argue with me. I've drawn my own conclusions on what I'll be getting in the future (probably not a Sony) and all I'm trying to say here is that we actually got treated quite well. There's no use in playing the outraged victim here if you don't do your research properly, it's just kind of sad.