Windows 95 two decades on: but why all the upgrades?

It's been 20 years since the launch of Microsoft's Windows 95 operating system, which changed the way we interacted with computers. But what was it that was so special about the software and why all the upgrades over the years?

http://www.abc.net.au/news/2015-08-24/windows-95-two-decades-on/6719818