When I first saw Linux in a dorm at MIT in 1995, I knew it was important. I wanted desperately to have an extra computer to put it on and learn it. Like most students I used my University's Unix main-frame for email to which I connected remotely from various computer cluster or labs across campus. Unix was completely different from windows or Mac OS, command line driven and was where the internet was. Back in those PC days the internet ran almost exclusively on Unix, if you wanted email, you had to use it.
Linux was an Operating System that allowed you to run a Unix shell clone on your personal computer instead of a huge mainframe or through a terminal. It was both great because it was completely configurable and free, but also a nightmare. You had to know a lot to really use it, and essentially needed an extra computer for it.
Around that time the internet moved away from Unix and into the web, and browsers. Netscape and Internet Explorer became the prime ways of interacting with the internet, and the necessity of Linux waned.
In the early-oughts I discovered something very cool. That Linux was now able to dual boot, so you could have it side-by-side Windows. This was great. I'd used the NeXT OS (NeXTStep) which later became the basis of Mac OS X and knew that Linux was a way to learn about the underlying system of Mac OS too. The more I looked into Linux with now easy-to-configure and free distributions like Fedora (Red Hat's community version) or openSuse (Novell Suse's community version) the more I thought this was going to take off big. As a person who has never pirated an operating system I feel the expense of getting one as quite significant. And I thought the model of open source would lead to great software.
And it sort of did. Linux came to dominate Servers. The computers that run the internet, displacing the previous Unix main-frames. But in the user space it remained marginal. Even with Ubuntu's massive success, it still remained in the fringes. But no more.
Linux and BSD (another open source Unix clone that lies at the heart of Mac OS) dominate the tablets.
Amazon's Kindle runs Linux, HP's WebOS is Linux, Google's Android is Linux, and Apple's iOS runs Mac OS (which is build on top of BSD, and very similar to Linux). So while none of this systems allow user direct access to the system OS, that I think will be a matter of time.