Ubuntu could have gone much further focusing on helping people learn to love the Unix CLI than trying to chase and reimplement GUI trends over and over for the last decade.
Anyone who wanted the CLI has had plenty of choices of various operating systems and distributions over the years. Ubuntu's strength is that it's useable and installable with a minimum amount of CLI. That means there's less of a barrier to newbies and casual users.
("Real" users can use blinking LEDs and chorded keyboards instead of fancy GUI cheats...)
People are by and large visual creatures so it makes sense that they would focus on the GUI rather than the CLI.
Though I agree that they were less innovative than I would have liked on the graphical side of things. However when they did 'innovate' with Unity people complained (and still do). Not a lot, but they were extremely vocal.
One of my pet peeves is that I think Linux users are disproportionately obsessed with the command line. A well designed GUI can actually be really powerful, but it seems like we compare well-designed CLIs to badly designed GUIs, decide that CLIs are amazing and keep not bothering to write good GUI apps.
That's not to say that CLIs aren't powerful - I have a terminal open all the time, and for many things it's the quickest option. But I think we underestimate how useful GUIs can be.
