Currently, colony defence relies mostly on knowledge you gain only after you play long enough, and even then that knowledge is mostly "stack defences so that you don't have to worry about it". There's no way to know your colony defences or raid/expedition strength in concrete numbers and no way to do anything about it in particular.
The player has no way of knowing how defensible his colony is currently. Ground defence can be checked remotely, at will, and has a tangible number you can affect by increasing stability and this part is fine. Space station is a bit worse, since while it's not hard to determine its strength, you can't do that in advance, and a bigger issue is that you can't remotely check the station's state or how long it will take it to repair. The worst offender are patrol buildings, since their contribution to security is not very clear and neither is their interaction with colony size. It makes it pretty hard to upgrade your defences in response to threats and it makes it more "spam all of those as soon as possible to avoid getting *** over".
The other part of the issue is that you have no idea how strong the enemy is going to be, either. Well, except for the raid/expedition/inspection being strong or weak, relatively, at the time you check the intel message. If we got more information about colony defences, those relative ratings would become more accurate as well, but I don't think it would hurt to be able to spy and obtain more accurate information. In addition to that, it should be possible to obtain information about incoming expeditions way earlier, giving the player enough time to do something with his colonies, if he cannot or does not want to deal with it personally. If knowing too much in advance would be too strong, perhaps spying should be suitably expensive or dangerous activity.
