I don't know what planet you're coming from, it may just be radically different galaxy settings, but Stellar Cartography means the ultimate difference between Victory and Defeat in a great many situations.
For instance, immense galaxy, rare stars, uncommon planets: send a colony ship on a 25-week journey to an empty star. Even WITH the tech, you can stumble on class 0 systems.
After I read this post last night, I started up a gigantic game, five opponents, rare systems, rare planets, rare habitable planets, and it's been the most fun I've had since picking the game back up last week.
I probably should have shut minor races off, but I totally forgot about them. They've been inconvenient about inhabiting approximately 75% of the unclaimed at the start planets, but I also had good luck. The one planet outside the Solar System I managed to colonize was a class 19 with two precursor archives, which put my tech development so far beyond everyone else's that it's not even funny. Later, I researched the ability to colonize water planets, landed on the one water planet in range (quality 8) and got a +700% and a +300% industry tile. I did miss out on a handful of resources, unfortunately, but have otherwise been doing much better than the other races (Altarian, Drengin, Arcean, Yor, Torian).
And stellar cartography (which was one of the first techs I researched) meant I did
not waste my time sending colony ships to planetless stars, of which there are many (relatively speaking).