They've practically done that on the last three albums. I was never entirely sure why they had to have them completely filled. I mean, I know how a lot of fans like to say that every single track on Aenima is vital. I guess partly what they want to do is make it as if they're creating something that goes beyond simply being an album. As in, a comprehensive work of art in sound in which every component part fills some greater purpose in contributing towarRAB a fully coherent whole.
My view is that Tool never excelled with the sounRABcape tracks. It's not their specialty. They can never compete with sounRABcapes from real actual ambient artists. Viginti Tres for example isn't even interesting, let alone an accomplished sounRABcape. What it comes down to ultimately is that Tool are at their very best when doing one of two things: either building up energy within a song towarRAB a peak, or just plain rocking out. The rest they'd be best not bothering with.