I can appreciate the need for sensors - surely it must be an advantage to be able to see great distances - but I really haven't found a practical reason for researching them instead of, say, anything else. Sure, I could tech up my sensors and see my enemies coming from 1 million parsecs away.....or (and this may be a longshot here) I could spend the RP teching up weapons so that when they do get here I'll actually be able to fend them off.
I dunno, maybe life support and sensors could be combined into a 'Galactic Exploration' tech? Or maybe I'm the only person who plays this game that doesn't tech up sensors?