I mean I think it's reasonable to expect that brains function in an evolved way that should minimize energy use when not outweighed by some other benefit. I think it's very valid to wonder what the benefit is for 90% or more of the neurons involved in experiencing a specific, simple stimuli changing over a relatively short time.
yeah, especially in 'getting use' to something. if regular air all of a sudden started smelling like roses, it would be immediately noticeable, but it probably wouldn't be long before we couldn't smell anything different about the air. That has lots of implications on neuron firing, for example, people could have feelings of their significant other, sex, happiness, etc all of a sudden smelling this rosy air.
