Has expansion become less important?

I really can't wait for the metal slider in the system editor to be unlocked.

Basic power,
Generator: You can build em anywhere on land and they always produce power, but if you want to support an advanced economy you will be spending a lot of metal and sprawling all over the place.
Tidal generator: Like the normal generator except placed on water. Possibly restricted to coastlines to make specific locations important.

Advanced power,
Antimatter reactor: Like the generator you can build them everywhere and they always produce power. Too bad they go nuclear when they get destroyed. Probably the best power for the cost, but keeping them defended, and at the same time safely away from your base might be hard. For lulz place two near each other and destroy one, causing a chain reaction. Note: this would be a smaller explosion than an actual nuke, but still enough to cause trouble if clustered together at the center of your base.
Geothermal generator: Produce as much power as the antimatter reactor, but can only be built on specific geothermal spots which work like metal spots only for energy. There is no real drawback to them except that you can only place them on points that you will probably end up fighting over.
Solar power station: Built in orbit, produces moderate amounts of power during the day, and none at night (Hope you brought energy storage!) Also extremely fragile, every unit that can attack orbital will destroy them in one hit.

No.... that is present in the mod you refer to. You have 30 fabbers selected, it shows you the total drain.

Yeah, I didn't believe him so I looked it up and ended up downloading it.

I like these ideas. Especially volatile advanced energy.

Tbh, I believe metal should always be the limiting factor. Right now it's only a question of who builds stuff faster, making the whole game stressful and unsatisfying since you (at least me..) always have the feeling of not using your resources effectively if you have enough energy. Both of your resources are in a huge surplus and bases become cluttered messes. I usually run out of space to build enough factories that could use up my resources...and that's only having built mexes on the metal spots in my starting area. Watching gameplay videos of other people and even developers I see the same thing.
I am quite surprised to see people who actually enjoy that type of gameplay ^^

Maybe we just need t3 power and mex, hell maybe! we could build a dyson sphere around the sun

I don't have a crazy amount of experience, but it seems that either metal extractors produce too much metal, energy plants don't produce enough energy, or fabricators require too much energy per metal to operate.

For testing purposes I captured a planet with the 50 standard (and currently unchangeable) metal spots and attempted to build enough energy to put all of it to use with fabricators. I failed, after covering nearly 1/8th of the planet's surface with T2 energy plants. Admittedly, I was using T2 air fabbers (to avoid roadblocks) which are slightly less efficient, but my 500 fabs ran out of power incredibly quickly trying to put all that metal to work.

500 T2 air fabbers can drain all the power from 330 T2 energy plants and they will do so regardless if you have metal or not. To use all the metal from 50 metal spots with both basic and advanced metal extractors on them with t2 air fabbers you need about 43 T2 energy plants.
Production of 50 metal spots: 7 basic income *50+ 28 advanced income *50 = 1750
T2 air fabber energy drain per metal: 3300 energy drain / 27 metal output = 122,2
Required amount of T2 energy plants: (1750 metal production * 122,2 energy drain) / 5000 energy production = 42.77

Lord, no! We sooner need to get rid of T2 Extractors and Generators -at least in their current form. If anything we need a bunch of T2 resource structures that bring some interesting trade-offs - like one of the 5 billion propositions made over the course of the forum's life span.

then can i haz more cybrans to kill and SHEILDS!

Uh, yes, I guess? Still totally enthused for proper ground based solar arrays - with day/night-cycle dependency and moons in orbit blocking your energy source and all that jazz.

After looking into the matter again, it seems I was playing on a randomly generated map that night, which had more than the maximum 50 metal spots in custom systems' planets. I performed the test again and found a planet with 108 metal spots. 108 x 35 =3780 metal income + 10 = 3790 metal. 3790/27 =140.3 T2 air fabricators. 141 x 3300 / 5000 = 93.06 T2 generators (the extra .06 made up by the commander himself) After constructing all these, I tested the setup with a nuke launcher (which could pump out a nuke every 8.5 seconds) and did indeed manage to get power and metal barely into the negatives.

I now believe that the number of metal spots generated on random maps is too high, and that is the driving force behind the lack of interest in expanding.

Yeah, I have come to this conclusion, too. The problem seems to be less about each extractor producing too much metal (T1) but more about the map generation itself. Currently most planets are covered with so many metal spots that you simply cannot use all of it effectively.
Hopefully this will change soon when Uber gets around to improving planet generation (the whole terrain should become a lot more interesting, actually).
I still question whether the gains from building a T2 extractor should be THAT big. I mean..its a few times as much metal as a T1 extractor with no downsides at all.

Hmm, I've always hated this mechanic in other RTS, but maybe the solution is to have metal spots be eventually depleted?

This always pissed me off in starcraft and age of empires, but there is a reason for it. It forces players to either expand, or win the game before running out of resources. As resources are consumed, things become more dire. If metal spots were depleted over time it would force players to continually expand.