It seems to me that of the 4 lower tier maps, Malinovka and Province are ideal for a defense deployment. Mines can go either way. Himmeldorf offers good choke points, but no real place to camp effectively.
The one guy that really caught my attention started Province by running out in the valley between the towns, while most everybody else took up defensive positions. When he was quickly killed (as would be expected), he spent the rest of the game complaining about everybody "camping" and that nobody provided him any help or support.
It seem to me that more inexperienced players would be playing the lower tier games and "camping" would be a players first instinct when just learning the game.....well, except for the fools that think it is a good idea to start Malinovka by crossing the open area in a slow tank.
The people who take up "defensive positions" and think they're so smart ... do not realize how much of a debt they owe to the more aggressive players. More aggressive players spot enemies for you, and achieve map control, ie- keep the enemy from controlling most of the map. If everyone on a team plays as you do, and camps near the base, it's a guaranteed loss, pretty much 100% of the time. The enemy's advance units will light your entire base for his big guns, which will pick you apart from beyond visual range.
In short, your strategy seems to work sometimes, but only because others make it possible for you to succeed by camping. You're like the banker who thinks he's so much smarter than the butcher, the baker, and the candlestick maker, because he makes more money than any of them. He doesn't realize that his income is only possible because he dips his hand into the stream of money generated by the economic activity of the worker bees that he thinks himself superior to.