I'm talking about this planet. How about you? You might want to go review human history. History is littered with examples where every capable body gets pressed into fighting for the survival of the village, city, or minor state. All the men, women, and children capable of being taught to do any useful task. Especially when they are facing an opponent that will put them all to death (or that they think will do so).
Heck, we don't have to go past the twentieth century to find examples where whole countries started drafting their women, first to fill non-combat and non-frontline roles, but latter included being in front-line positions and even front-line combat positions. Heck, it's common practice to this day to "draft" (forcibly conscript) boys as young as 6 in parts of Africa.
And that's just us humans. For a non-mammal style race that is born/hatches whole and needs very little time to learn to move, how fast could they be taught skills to support the war, or even fight? Natural carnivore species could have some decent HTH capability or ambushing capability "out of the egg" as it were.
And are you going to argue that the Yor, a completely artificial race, wouldn't fight to the last 'droid if they thought it would suit their greater designs or needs?
However, the point that the planetary invasion system is simple is very true. This does mean that we don't have to worry very much about the micro-managing of armies and such other then building some transports and shovelling people into them, and sending them out to where we want to invade. While that simplicity stands out, I'm not convinced that "improving" it would bring any more joy to the GC players.
Consider, MoO3 had a system where you built a variety of ground units, and would scoop them up on transports, and send them out. Then you'd invade your enemy worlds. That was a simplistic tactical system, and being such, meant you could always maximize/exploit the world invading to make it trivial to take over worlds. And the truth is, that was actually well done in MoO3.
Last night, I was playing a game of GC2 beta where I was invading a technologically superior opponent (with a x3 tech edge over me). My 1000M (1 billion) troopers were still eliminating 2000M (2 billiion) or more of the enemy with each assault. An invading army, versus presumably dug in local defenders. It should have been the other way around (ie, my 1000 should have only eliminated something like 300 at even RNG results, considering the massive tech edge they had over me by the shown fighting stats). So... what's that mean? It means that most of the citizens on the ground aren't actually trained. They must have been charging out with their hoes and skillets against my troopers. Because a prepared army defending their home land that had any time to prepare should have easily wiped out my forces. Of course, that would make for a boring *game* as it would mean that you could never take out an opponent if they got a decent fighting edge on you. Definately not fun if the determined under-tech but massive numbers cannot overcome the tech elite but less numerous force. Don't you agree?
As a final point, during the 15th such assault I had sent in (it was a huge homeworld), as I watched my troopers dwindle in number, it occurred to why the transports are always destroyed when the assault force goes in. To prevent them from jumping back in and running. Those invading troopers are committed to winning, or dieing. That means they will fight a lot more viciously then "normal". That means they will inflict a whole lot more damage and casualties, and not just on the properly uniformed enemy. Such is the way of the one-way drops.
Should the system be changed? Only if it adds to the fun. I can live with it being simplistic, as I am finding that GC2 is already a longer play then GC1. Adding a new layer to the game that lengthens that play further that doesn't add to the fun might tip the game from playable to "too tedious". And once that happens, all the "too tedious" players would be calling for orbital bombardment (so they wouldn't have to deal with the tedious invasions), and orbital bombardment leads to biggest galactic bomber force always wins. Not the aimed for fun of the game, according to Brad.
