If the brickfilm was supposed to be cartoonish in style, then I guess it would work. I think a lot of brickfilmers strive for relative 'realism' though. Also, if you have a 3D element, it's easy to render that from different angles. 2D is a lot harder to get right in that respect.

"Nothing goes down 'less I'm involved. No nuggets. No onion rings. No nothin'. A cheeseburger gets sold in the park, I want in! You got fat while we starved on the streets...now it's my turn!" -Harley Morenstein

A big thing with 2D animation and stop motion is to have the right idea. brickfilms with 2D isn't done much (or at all) because you could just make a stop-motion. Plus it would be really hard to do Lego in 2d because it's so 3D and would require sooo much perspective work. But to see a brickfilm with 2D animation would be really amazing. Also, watch this video where the director of my favorite 2D animation movie give a short BTS: http://youtu.be/ILpNlfO6qMg

Cool idea, but it is a lot more work to make 2-D animation than it is Lego, in my opinion.  Having worked in both pen & Ink 2D and now Lego, I weighed the advantages myself while new at brickfilming:

The primary advantage to brickfilming is that the animator doesn't have to redraw the characters every time they make a new movement.

The primary advantage to traditional animation is that the animator can reuse animatoon cycles on new backgrounds without having to redraw anything.  For instance, a bunch of cells with a character's walk cycle can be placed on any other background anf be reused anywhere.  Also, the animator only has to make the character make two steps and the cycle can be repeated to make the character walk endlessly.  In Lego animation, if a character is walking across a room, he must be animated for every step he takes.