I can see where you are coming from in regards to planned obsolescence, but I can't really agree to that. There are at least around 5 years or so between widespread adoption of those features in hardware and actual dependence on those features. If Software had been creeping up a year or less after introduction that depended on those features I could easily see this, but in this case there is enough of a market saturation of compatible hardware already that this theory seems rather unfounded. it is only a handful of games anyway that depend on that. A cursory research about SSE 4.x dependence has turned up Quantum break (Xbox one/PC cross buy, no idea about the steam version), Gears of War 4 (Xbox one cross buy), Mafia III, MGS 5 (patch seems to have removed the dependence) and no mans sky (seems to be patched out, don't know, don't care either). That looks more to me like the developers actually catching up with the market. Considering they have patched that out in 2 of the cases chances are they are not strictly needed, but if using them is simpler, faster or more convenient than alternatives, that might already be argument enough to use it if the hardware is common enough to support it. don't forget that there are pretty much no CPUs manufactured anymore without those instructions, even modern atom CPUs include SSE 4.x. And honestly, while it is nice in theory, you can't expect old, outdated and no longer manufactured hardware to be supported indefinitely.
Don't get me wrong, planned obsolescence is most certainly a thing, and a very nasty one at that, but at least in the PC market I just can't see it as being a major factor. The usable lifetime of most hardware, outside of outright broken components, is just way to long to give that credence as a motivating factor in most cases.
As for the Console CPU core count, I think those fears are rather unfounded. The Part about the console CPUS that most people and especially fanboys like to forget is the fact that thos "jaguar" cores are AMDs Atom equivalent. Low power, low performance but more cores. pretty much all modern quad core or higher CPUs (i5/i7/fx series) are way more powerful than the 8 core console CPUs to the point that even if the games use as many threads as the consoles have CPU cores, there is no way the desktop CPUs will perform slower.