I think "not common" is a bit of an understatement if I don't find at least 1 in my home system.  Doesn't matter how powerful they are if you never find one.  Also tends to make some of the Precursor technologies not very helpful unless you find a relic.

I really didn't think they were that over abundant in the base game.  Maybe dial down the bonus and make them a little more common would be a good compromise.  

If you are referring to "Artifacts", I can see one in your screen snapshot about a quarter of the way in from the right and a little above center vertically.

Is the below screen snapshot the item you are referring to?  If not, can someone provide a screen snapshot of what a "Relic" is?

Quoting PaulLach,

reply 7

Is this what you are talking about?

Yes this is the "Relics" we're talking about.  I'm in my 4th game and have never found one in my home system.  Just seems a little too "Rare" for my taste.  When things are rare and offer powerful buffs, the lucky Civ gets an advantage I can only overcome by conquest.  However since that's my ultimate intention maybe it doesn't really matter in the end   

So here there are 2.  I'd probably expect there to be 3 to 4 so I'll bump that.

Is that from a small universe setting?  If I'm playing max size would that account for the odds going down for any one sector seeing a relic?

This was just a small map.  Resources and such are based on the size of the map.  bigger the map, the more stuff.

Yes, that's how it worked in the base game, but they changed the frequency of relics appearing so that doesn't happen in Supernova.