- It turns out that one still can download the ISOs for Win 10, Win 8.1 & Win 7. And it's all 100% legal, from the MS websites. MS only has hidden those ISOs rather well. Some smart folks even have made a tool to make downloading those ISOs much easier. The website "How to Geek" has all the details.
http://www.howtogeek.com/186775/how-to-download-windows-7-8-and-8.1-installation-media-legally/
I've never found them hard to find.
Still freely available right off the MS download centre pages; https://www.microsoft.com/en-au/software-download/windows7 and it provides the links for Win10, 8.1 and 7.
As always, the ISO's are free and legal, you just need a Product Key or a digital entitlement from a previous version.
- @MTA: That website only provides the ISO when the user has a retail version of Win 7, not when one has a OEM version. But the tool (see post #1) doesn't bother and provides the ISO, even when the user has a OEM version.