I loved playing with Legos as a kid. What kid didn't, right? This is probably the appeal of Lego movies - taking something we're all familiar with, particularly for creating our own worlds and acting them out, and using it in a creative art form, sort of acting out something that existed only in our heads before.
A friend shared this video with me last night - Ghostbusters, acted out by Legos. It's pretty awesome:
Of course, just because something uses a familiar medium doesn't mean it will be successful. It also has to not suck (warning: video NSFW):