This is feedback from the perspective of a new player to the game. I've played the game for only a few months, but I feel like my perspective on this issue will help to improve the game's appeal to other new players.
The first time I was attacked by another player, my base was completely destroyed without dealing more than 1% damage to the attacking fleet. I've played a good number of other games similar to Battle Pirates though; I half expected to make a ton of mistakes early on so I tried to learn from it and prepare accordingly. Something I noticed after this was that my base level would increase as I did ANYTHING at all, which simply opened me up to attacks from higher level opponents. Every time I was attacked, it seemed more and more hopeless. The attacking enemy fleet would always be comprised of five identical ships that would simply stack together and charge through my base channel leveling every ship and structure, sometimes without taking a single point of damage. Now, I know that I'm not the best player by any means, but these base attacks are too one sided, especially considering the absence of any offensive strategy or ship diversity by the attacker.
After joining an alliance, some more experienced players informed me that I was probably being "farmed" by higher level players, and that there was truly no chance that I could ever defend my base until I got to a much higher level. So... this meant that a solution to the problem existed, but it would be at least a year down the road. Now, as game developers, you guys have to admit that this situation is very non-conducive to recruiting new players to the game. I'm not saying that new players should be able to easily tango with older players, but if the game seems to be broken for the entire first year of play, how in the world are you going to pull new people in and make them want to invest real money?
The answer to the question in this post's title is "yes", but not for new players. It's incredibly frustrating to hit your head against a brick wall trying to amp up your base defense assuming that you're doing something wrong, when you're just going to get unavoidably wrecked every day, your resources stolen, and have no recourse whatsoever. When you finally manage to repair and gather some resources, you'll find that you've just leveled up your base, and are now a viable target to even higher level opponents. You've basically just done all that work in order to "donate" more resources to your enemies.
Here are some general solutions to this that are inspired by some other games I've played:
1. Command Points
This is a resource that needs to be consumed in order for players to attack each other. Players accumulate this resource at a fixed rate, and they can store a couple days worth at a time. Attacks cost the same amount of command points regardless of the level difference between attacker and defender. What this does is increase the incentive for players to attack others of similar level, while still giving them the option to attack lower levels. Currently, there is no cost at all for high level fleets to bowl through hundreds of low level bases at a time, but if attacks cost command points, the attacker would want to optimize their usage of attacks. A player who chooses to attack low level people constantly will fall behind. You could probably get rid of any level-range limitation on attacks if you did something like this, and you wouldn't have to do any "stat crunch" either.
2. Increase the armor of all base defenses
Battle Pirates is the kind of game that should encourage large scale PvP raids. At present, attacking fleets can typically get in and out too quickly, even if attacking many bases in succession. This entire time scale should be stretched out to the point where it is more common to see multiple fleets or multiple attacks to take out a similar level base defense. It should NOT be so commonplace for players to log in to find their base and twenty other bases near them destroyed by a single enemy fleet. Slow that whole process down, and you'll see larger scale wars going on.
3. Make equipping structures happen separately from building/upgrading
This works very well in VEGA Conflict, and there's good reason for it. If we could simultaneously equip a turret and upgrade another structure, new players might not be so utterly screwed. Think of how crippling the current shared timer between equipping and upgrading is. We might as well not even touch our defenses until we have the best possible stuff in the game, ESPECIALLY since we don't even get a partial refund of equipment we replace. If we ever bothered to equip a Sentinel Missile III to a turret, we've just flushed all those resources down the toilet, and we've stunted our growth in other ways.
4. Partially refund the value of replaced equipment on structures and ships
Without getting at least a partial refund once we replace our lower level weapons with higher ones, what reason do we have to even bother with the lower level ones in the first place? Almost everyone who plays at higher levels will advise a new player to completely ignore their defenses, and this is just one of the reasons why. Any low level investment is a complete and utter unrecoverable resource dump, and this is to say nothing of the fact that they are also completely ineffective.