Sensation and perception is a limited view and also the only point of access to reality we have. This said, then, we should think it is important. No sensation and perception necessarily means no understanding of and no interaction with reality.
This is, of course, if there is another reality that is unknown. But why complicate things when one reality is already complicated enough. Reality has no cause for being more complex than need be.
The onus is on others to explain why the metaphysical is needed.
I am happy with a mechanistic explanation of us. That the illusion of a self or rationality should be no less plausible than phenomena or representation. To react against the physical reality is really an unnecessary fear that brings about more grief than relief.
As a Buddhist correct understand brings about relief. The explanation is not that different to a philosophically material monist one. The self is not what it seems. A soul is as plausible as a non-soul. To discount non-self is not scientific, not open-minded. It is foreign. It is The Other.
It should be noted, firstly, that the concept of Emptiness (shunyata) does not exist in the Theravada tradition of Buddhism. It is a Mahayana Buddhist term. The term closest to Emptiness in Theravada Buddhism is Non-self (anatman). So why these separate terms?
In Theravada Buddhism the Buddha’s teaching of Non-self is interpreted to mean only no essence of the self, the sentient being. Mahayana Buddhism interprets Non-self to mean all things, animate as well as inanimate. This is why Mahayana Buddhists to distance themselves from the term No-self by taking a word to cover the wider definition they believed the teaching of Non-self to mean.
This is why Form and Emptiness are spoken within the same breath in the Heart Sutra. Whether one accepts the Theravada or Mahayana is up to the individual. What is important is to know at least this difference exists in Buddhism. It is a matter of interpretation.