Are you suggesting these spin-offs are (always?) after-the-fact justifications using issues that were not pressing concerns?
The problem with attempting to justify space exploration with spin-off examples like food preservation is that it risks provoking a 'so what?' response. Piling on unimpressive claims does not strengthen one's argument, it dilutes it, and gives the opposition an easy target to dispute.
When Clarke came up with the idea of communications satellites, he, and others, thought he had come up with a before-the-fact justification for space travel, as he expected these relays would need regular maintenance, but another claimed-spinoff-but-not-really, semiconductor electronics, obviated the need.
The problem with attempting to justify space exploration with spin-off examples like food preservation is that it risks provoking a 'so what?' response. Piling on unimpressive claims does not strengthen one's argument, it dilutes it, and gives the opposition an easy target to dispute.
When Clarke came up with the idea of communications satellites, he, and others, thought he had come up with a before-the-fact justification for space travel, as he expected these relays would need regular maintenance, but another claimed-spinoff-but-not-really, semiconductor electronics, obviated the need.