Absolutely -- yes Windows came with your PC, but you'd buy the new version as a (cheaper) upgrade if you didn't want to wait until the next PC you bought.
Today new OS versions aren't such a big deal, but when Windows 95 came out, and then XP, they were huge, with total interface redesigns.
On the other hand, I don't think people went out of their way as much to buy smaller upgrades like Windows 98.
I think the fact that OS updates are free now kinda killed a lot of the marketing/promotion since most consumers will only update if their computer is old.
Today new OS versions aren't such a big deal, but when Windows 95 came out, and then XP, they were huge, with total interface redesigns.
On the other hand, I don't think people went out of their way as much to buy smaller upgrades like Windows 98.