Are planets and population actually useful ?

[GAGA Extrem]

Population gives you:
(I) Border Range
(II) Naval Force Limit
(III) Flexible and powerful yield options

 

[GAGA Extrem]

[...]
It is a bit weird that Paradox went back to tying size and tech again though considering they dropped it after EU3.

I am not too unhappy, considering that it worked really well in EU3, particularly for Stability.

 

[GAGA Extrem]

I don't mind that population has to be managed for happiness and ethics and rebellion and whatever. But I want all this to feel worth it. I want it to be the other side of the coin, not the only side. I want to feel that my population is what makes my empire strong, what make my empire period.

But... That's how it works already.
Offworld Stations are good early on because they can circumvent pop requirements and the tech penalty, but a well developed planet is much, much stronger in the long run.