Yep, Ive never found much fun in fighting against others. And this goes way back a long time ago at a LAN party we once had. it turned really sour when one of the players was really good at Quake 2 DM and was killing one of the other guys. not intentional, he just happened be the one that got killed by him a lot. he got really upset and pushed his monitor into another guys monitor. and things went bad. so from that point on we as friends decided there would be no more DM games, that we would only play against the AI. and it hasnt failed us yet.
But again, you can still do what you want in the back area by building a Starbase abnd lots of defense to protect it. but by the time another player got to the cannon, you would have killed a bunch of his planets anyway. but as I said, i took them out of the game and made them into Ion Cannons, they work so much better and are a lot more viable like that if you ask me. My Friends even agree and like them too.