They don't confer any abilities or unlock stuff
Not true.
Altarian: Social Matrix
Arcean: Stellar Forge, Lite Constructor Module
Drath: Nothing
Drengin: Arena, Basic Slave Pit, Black Market (essentially basic improvements for their tree)
Iconian: Dream Conclave, Precursor Archive
Korath: Arena, Basic Slave Pit, Black Market (essentially basic improvements for their tree)
Korx: Nothing
Krynn: Consulate
Terran: Market Center/Innovation Complex
Thalan: Economic Direction Unit, Temporal Entertainment (Hyperion Matrix)
Torian: Market Center/Aquatic Transport Station, Central Mine, Harvester, School, Temple of Memories
Yor: Basic Stalk, Collective, Maintenance Grid, Research Matrix
And that's not even counting the other two Iconian techs that unlock things very early on, or research in anyone's tree, namely but not limited to the Drengin and Korath, or Industrial Revolution, which almost but not quite everyone gets.
It establishes a "design", or if you'd prefer a "theme" for their improvements, and in most but not all cases gives you access to the basic ones.
And while GrnDragn is not quite correct that they don't cost anything, the vast majority of them are close to free, while the others are free.
Furthermore, since you start with them @ the beginning of the game, there is no way to see the information they contain unless you look at the XMLs or have something like Galactopedia!
Also not true. Open up the tech tree, hit the button in the bottom left hand corner that allows you to see the whole tree, and drag it to the left until you see the techs in question-which you've already researched, or chosen at the start of the game-and satisfy your curiosity.