I'm relieved that transmitting doesn't decrease the total amount of science you can get. Otherwise you'd never want to send a probe before a manned mission, which would be broken. I like that the devs took the time to get that right. For fixing the problem with spamming transmissions, it seems sufficient to just disallow transmitting the same data twice on the same mission. Yes, you could still spam probes to get the same total science, but doing so is boring and time consuming. In the real world, for many experiments, recovering the equipment isn't all that useful (what would we gain from the Voyager probes returning home?). The bonus science for returned experiments is purely a gameplay mechanism to reward harder missions. To that end, this is something we can all just implement ourselves. Don't transmit the same data twice on a single missions. Solved.
