This is exactly right. It's not a war game, but if you're trying to establish the best empire, it makes sense that conquering other civilizations should be a huge benefit to your empire. It'd be stupid and unrealistic if conquest was not a huge benefit to your civilization. However, the problem right now is conquest is so easy because the AI is so bad that it makes conquest too tempting. If the AI was adequate in combat, it would make war less tempting because you'd have more to lose.