If you need something to hate on them (and they absolutely deserve it for way more than just this, it just stands out as an obvious one) - they put adverts in the start menu, and they were still present in Windows 10.
Oh MS the company deserved the hate - and still does - even if Windows the OS (or at least Win2k SP4, WinXP SP3 and Windows 7) became pretty solid and dependable.
On the other hand, IE6 held web developers back from bloating their sites and turning them into "apps" when all the users want are a document with maybe a little interactivity here and there.
I feel strange about hating on MS after the 2000s