I feel like the logic for Hawkins goes like this.
By far the Exeter is overpowered (to some, not necessarily including the author) at tier V, even if WG removes the heal. Look, Exeter has not only the best winrate of tier V cruisers, but also the greatest average damage, highest experience per battle, most plane kills per match, and most kills per death by significant margins. Not to mention, it has the second most kills a match; the stats are crazy for this ship!
On a secondary note, @LittleWhiteMouse concurs extremely strongly
So how does one make a balanced ship out of Exeter? Uh... I don't know, I'm going into fantasy land. But there are a few avenues...
Lower the damage
This is self-explanatory, I think. Often, this means decreasing the bursting charge.
Remove the heal
That would remove more than 19000 potential hit points, which in addition to the ship's starting hitpoints make the ship extremely durable.
Heighten the citadel
Not only is the ship durable, but she is not as easy to eliminate as other tier V cruisers. Like most of her counterparts, her citadel is defended by a 76 millimeter belt. However, Exeter's citadel is comparatively low and small relative to them, especially Omaha and Emerald, making it harder to hit. Heightening the citadel would make this belt easier to hit.
This is also self-explanatory. You're going to get hit more by not only planes, but the people the planes are spotting for.
What happens if you choose avenues 1, 3, and 4? You get a ship close to Hawkins, except with a different turret arrangement.