Well I had a game for the first time with the artifacts in play, they are a fun thing in the start of the game when people are trying to get them, but then they loose their flair.
So my group and I talked about making the artifacts more important, by giving them some abilities. We didn't talk about what they should be but here are some of my thoughts, just to make them stronger targets.
Precursor fossil: You can buy shock troops instead of normal ground forces.
Ancient Shipyard: The planet functions as a spacedock, you just don't have to place a spacedock unit on the planet, but is subject to all other rules. Except the possibility to destroy it with an action card.
Datacash: You gain a free tech, and all techs cost two resources less.
Ancient armoury: +1 on all combat rolls.
Just an idea to make them more attractive to get a hold off.