That plants do not have a nervous system comparable to animals is of zero relevance to the whole argument.
If we follow your arguments, we'd have to affirm that destroying rocks make them suffer and that we can not imagine their subjective reality. That's wrong. The lack of a nervous system makes plants automatic beings, with a simple life that serves no other purpose than living, and there's no "emotions" needed to carry that task, just like in bacteria.
Sorry, but you did not get my argument. I'm not claiming that plants or rocks suffer in a human/animal sense. In fact I'm saying that the concept of suffering should not be applied to them because we (as organisms/matter of a different kind) can not fully understand their true nature. Therefore we have no moral justification to kill/destroy them while we spare animals.
All these things have equal right of existence. There is no moral justification only to kill what's dissimilar to us while protecting what we pity.
ya.ya.yo!