Right now, fighting on the same planet is relatively balanced compared to interplanetary fighting. Right now, it is almost impossible to attack a fortress moon. It is very difficult to make planetfall of any kind if someone semi-competent is already there. The ONLY option is orbital attack lasers, which are 1. Mega expensive 2. Cannot hit moving units. 3. You need 5 to kill one stupid catapault (note: 1 orbital laser is way more expensive than a cata).
I imagine that eventually, a space-based factory will be constructible. Said factory would be able to produce interplanetary warships (perhaps not ones that can enter the atmosphere, but they can still be quite potent). Naturally, at least one of said warships would have the capability to bombard a planet. And could perhaps do so more effectively then the orbital laser. That said, the space-construction ship that must be launched from the launch pad to BUILD space-ports would be the most expensive thing the land-based launcher can build (and naturally, space would be a difficult environment for nanolathing or whatever we call it now to function, so building an orbital factory would take a while too). So as to make land-launched satelites and space fighters still be viable as something you make for an early advantage in space. But, you would also be able to spend time and resources to get some things that can really punch through planetary defenses if need be. That's my basic take on it anyway.
It would probably be best if you based your take on the confirmed features list. (warships are confirmed to NOT be a feature)
Why isn't this fixed? Because this is BETA. The game is under development. It isn't complete. Uber is working hard on orbital interaction. It isn't a quick easy addition. In the meantime, just play on a single planet system. That's what I do.
In the meantime don't take the game too seriously. But it is beta. If you need, agree on gentlemen's rules ahead of time (and that can include playing on one planet or playing on multiple smallest setting planets and agreeing not to move commander to them and if they break rules just leave and consider it a win because it isn't tracked anyway) This game has one functioning space travel unit. It is basic planned features to have at least some form of mass transport. They are talking heavily on teleportation gates, where units simply walk between planet surfaces. They also mention a cannon to fire units at other planets, rockets to launch single units to other planets, and transports fitting multiple units at once and dumping them all on another planet (doing multiple of them dumps multiple on the planet, you get the idea, mass invasion Red Alert 2 Soviet style)
FYI a laser does 2000 per shot so takes out a catapult in one hit. Orbital is undergoing some big changes (to be announced) and the units for interplanetary warfare aren't added yet: Teleporters, Interplanetary nukes, Unit cannon
Brian: The definition of insanity, is doing the same thing over and over, and expecting different results (Albert Einstein)