You're entitled to your opinions. Our #1 priority is the millions of students who use our content and testify that it is measurably helping them. And to be clear, they aren't deluding themselves--read our comments and you'll see student after student using our content to rock any assessment thrown at them. The data we're seeing in pilot classrooms is showing students performing several grade levels ahead. We're seeing remedial students using Khan Academy software leap frogging non-remedial students. Very savvy school districts (with super demanding parents) that understand results are rolling us out on a district-wide basis.
As for conceptual understanding, this is what the Khan Academy is all about. We have multiple videos on proofs and conceptual understanding that are never touched on in most classrooms. I won't make a lesson unless I can explain the why and/or why it is intuitive.
As for your "research", what is it tangibly doing for students? Rather than talk, we think we should build, learn and iterate.