While I agree that OEM computers come installed with a lot of crap, that's not a Windows problem, that's an OEM problem.
Windows is as successful as it is because of Microsoft's cooperation with crappy OEMs who are only too happy to betray their customers for a quick buck.
You can't have Windows without the OEMs - show me the Microsoft PC you plan to buy. Microsoft does the best they can, working within their constraints, but at the end of the day they're throwing their product over the fence and letting someone else package it.
And you can't have good OEMs because Microsoft's PC strategy - with WHQL, PNP, UEFI, ACPI, and just about every other hardware initiative they've participated in, has been to make it difficult for hardware manufacturers to innovate in creative, non-standard ways without Microsoft's prior consent. Hence the race to the bottom among PC manufacturers. Cheap PCs, yes, but there's not much room for innovation that hasn't been green-lighted in some way by Microsoft and so the only PC manufacturers who do well are those who can survive on thin margins.
If you go back and carefully read my post, I said nothing about whether Microsoft could 'dictate' to the OEMs - only that Microsoft doesn't want to sell hardware PCs and that hardware PC OEMs are almost necessarily bad because the market for PCs rewards low price and hardware component stats, not the overall usability, quality, or unique innovation of the product.
Microsoft under Gates and Balmer demonstrated very clearly that they couldn't be trusted to exert their influence over the hardware OEMs. They couldn't resist using their power to hammer small start-ups selling potentially threatening new technologies. So yes, they've lost this lever that might otherwise have been used to protect PC buyers.