A mod is any modification of, addition to, or subtraction from, the base assets. When you adjust your planets with the options, you are adding no assets. When you add a custom portrait, background, etc, you are adding assets. You can argue that since you actually have to add those assets outside of the customizer to use them it's not a mod, but when you create a custom race, even without adding other assets, you are still generating a new asset. That custom race file is a new asset, it doesn't exist in the vanilla game, you have to make it. The ship builder is a mod tool as well. If someone used the ship builder to make a vessel with so many polygons and moving parts that just a single one could cripple performance, it wouldn't be the game's fault, it would be the modder's fault. If you add so many custom races that you no longer feel the map is expansive enough for your tastes, it's not the game's fault, it's yours.
The game supports 100 players on it's largest map with abundant settings, with room to spare, it still would with half the planets, I played entire games of GC2 with only three planets. That anyone is whining about how they don't feel they have enough habitable planets is just a sign that people are narcissistic assholes with too much time on their hands and too little respect for themselves. It's sad, I'm not even amused by this thread, and I enjoy pointing out the stupidity of others because I'm an asshole myself.
Now, if you want to declare yourself in favor of games being released in a polished state, and don't think "evolving" a 4X should include simple typo fixes, then you've got something to harp on. You wont find me telling people off for thinking there is an absurd number of bugs even after multiple patches. For myself, I'm not happy with the state of things in PC games at all, it may not be Elemental(and it's not, people with delusions to the contrary should give themselves a history refresher on just how horribly fucked Elemental was at launch, this is just Stardock normal, a whole host of other companies use this standard as well), but the reasons given for Elemental's state don't exist anymore. This game could have easily been 90% plus in Steam reviews with another month or two of polish. It became the norm with publishers and shelf dates forcing a product to market even though it wasn't ready, but a digital only, self published release, doesn't have that excuse anymore, and people know it, so off the negative reviews go. Paradox is another great company that just loves to give themselves the shaft by creating more bugs than they fix with each expansion to CK2. I can only imagine how many people look at that game when a new DLC puts it back in high visibility, think it looks great, pop into the forum to see what the community is like, and run screaming after they see multiple pages of "You broke your shit again" posts from people irked over yet another alpha testing job they've been handed.
I find Blizzard to be an unimaginative, dull company, but they've got one thing right, polish first, release second.