I don't think it's illegal for hardware partners to ask Microsoft to give users reasons to buy new hardware. And of course they do this, they always have. The Wintel alliance has always been a symbiotic relationship between Microsoft and the hardware OEMs:

- Hardware guys make cool new hardware that incentivizes PC sales.

- Windows guys add driver and OS support in a timely manner so apps can utilize it easily.

And sometimes the other way around:

- Windows guys add some cool new feature that incentivizes PC sales.

- Hardware guys drive down component costs to compensate for the OS getting bigger and slower.

The problem for the PC industry is that in the last ~15 years or so this virtuous circle has broken down. Outside of Apple the hardware guys stopped coming up with cool new features that would shift units outside of gaming GPU upgrades, and gaming has anyway been dominated by consoles for a long time exactly because they have hardware DRM that works so game developers prefer it (also gamers when they want multiplayer without wallhackers). Intel struggled and AMD didn't really pick up the slack in any major way. Even Apple has struggled here - other than their proprietary CPU designs and rolling back some Ive-isms by adding more ports again, a modern MacBook isn't substantially different than the models they were selling years ago.

So that leaves the software guys to drive sales. Unfortunately for the PC OEMs Microsoft has well and truly run out of steam here. Their best people all left the Windows team years ago, and Windows isn't even a top level division anymore, being weirdly split between the Office and Azure teams.

A big part of the stagnation is driven by the web. Nobody writes Windows apps anymore except games, so there's no progress to be had by adding new Windows APIs outside of DirectX. Meanwhile the web guys are shooting the PC industry in the face with a policy of never adding features unless it's supported on every piece of hardware from every vendor, more or less, which makes competitive differentiation impossible, so nobody even tries anymore. There is no web equivalent of a driver since the Netscape plugin API was killed. They also move incredibly slowly due to the desire to sandbox everything. In the 90s the success of Windows was driven by some wizard-level hackers but as PC hardware matured clever tricks stopped being an important differentiator, and monopoly profits made them fat and lazy. It's clear that Nadella has zero confidence in the Windows org(s) ability to execute, hence why in the post-Ballmer years the rest of Microsoft has systematically divorced itself from them.

So - no hardware innovation thanks to the web, no major CPU upgrades thanks to Intel/AMD, no software innovation thanks to Microsoft. The PC industry is stagnant and desperate. What have they got left? Well, they have TPMs (really, TPM v2 because TPM v1 was kinda botched). And Windows doesn't really need it, but if Microsoft ties Windows upgrades to TPMv2 they can use the treadmill of security/support expiring on Win10 to drive one last round of hardware replacements that can give the industry an injection of revenue that can then maybe be spent on finding new hardware features to drive upgrades, seeing as Microsoft can no longer do it.

There's nothing illegal in any of this - nobody is price setting and it's not much different to prior eras when new Windows versions required more RAM.