The complaints are from the players on the top of the iceberg (GA junkies). I can assure you, that 99% of the players absolutely love the +15s, or any other offensive help...
The game must be offense oriented. You can't defend when you log in. You can only attack. Offense is the funny part.
It shall not be too easy to 5 star (and it is not, all those who are complaining here, that it's too easy did atl. 20k+ attacks already - hell lot of practicing, if you ask me), but shall be still doable, after so much practicing.
The 5 star gives the casual players the enjoyment, and NEXON wants them to come back more and more.
The Big guns (from the mentioned alliances) are coming anyways, NEXON must attract those, who are not hooked yet. And NEXON must prepare the dish for them.
If the defenses would be stronger, the enjoyment of the casual players (99%) would decrease.
Please still remember, that by the current setings ww and multiplayer should be playable both. If you buff the defenses for war (where you throw the kitchen sink at your opponent) - multiplayer would be unplayable