I admit, it hits me whenever somebody from the original cast dies and I'll probably feel the same way about Star Trek: The Next Generation and Voyager.
The whole Star Trek vision and, believe me, some of it has its problems, has always struck me as a bit of necessary hope in a society that can very easily turn cranky. The whole show, and Nimoy embodied this, has always been about humanity overcoming its want for resources and its inane and unproductive tribalisms.