The clip below is of Terry Gilliam running you through his entire process of creating cut-out animation. What strikes me most about it is that he spends the opening part of the show lampooning his 'laziness' and then emphasizes that he chose cut-out animation because it was the "quickest and easiest form of animation that I know".
As you watch, if you're familiar with GoAnimate's Studio, you'll realize that all of Terry's process could be done with Photoshop and GoAnimate. Not only that but you could make the process even quicker and easier since, with GoAnimate, you'd no longer have to painstakingly shoot every single frame.
Back in the day Terry's animation was considered revolutionary yet I doubt few people (beyond Terry himself) would have called him lazy, lacking in talent or uncreative for appropriating many of his backgrounds, characters and props from magazines, books, popular culture and even other artists work (cupid's foot anyone?).
Though he did actually draw and create many of his cut out characters, much of his animation work is simply manipulating props and characters taken from other sources such as the Christmas card example shown in the video.
I'm not saying the work produced by the majority of GoAnimators is on the same level as Terry's work. I wouldn't rate even the best GoAnimators on Terry's level - not even 1960's Terry Gilliam. However, after watching the above video, imagine how much more Terry might have done if he had access to GoAnimate and Photoshop back then, when animation was his central medium of choice.
What this video shows is what I've always thought about GoAnimate and Terry's similar animation techniques (since I'm a die hard Monty Python fan and have been familiar with Terry's work for almost as long as I've been alive). In the right hands and with the right creative mind GoAnimate could easily be a serious animation tool.
You may not make a feature film using GoAnimate's existing preset graphics but an artist importing their own style of art into the GoAnimate studio could do some amazing stuff... and never need to 'get flash or something'.