Yes there are some very important lessons to be learned.
Spanish Main-The finest of all sets in my opinion, had tons of unique crew and abilities. However there were problems with extra actions, most notably from Blackheart
Crimson Coast-Power creep begins here. Ships get faster, more chances for extra actions
Revolution-Game hits rock bottom as far as I'm concerned; introduces broken mechanics like the Firepot specialist and broken ships like the Banshee's Cry. The game never fully recovers and this is the last set with power creep.
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Barbary Coast- Wouldn't you know it, ships get even faster! However abilities are toned down and so are cannon rolls. Now from now on Pirates will have slower ships, and will be on a power decrease. Island ranges are extended from I believe 2L to 3L.
South China Seas- Not exactly a spectacular set but the Jade Rebellion is the best of the one-off factions because it got some really good crew. Most people didn't actually like the set when it first came out.
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Davy Jones' Curse- Ships get slower, stuff is less powerful for the most part.
Mysterious Islands- Ships get slower, Mercenaries just stink because they can't gold run as they can't dock at their HI. One of the low points of the game.
Frozen North- See DJC
Ocean's Edge- Another low point of the game, but has a few powerful and fast ships. However the game sinks even lower...
PotC- If Rev was a low point of the game for being OP, this set goes even lower for just being a lame set. No factions but England or Pirates, and they both get stuff they shouldn't have as it makes the factions too powerful(Endeavour and Mercer for England, Tia Dalma for Pirates)
Rise of the Fiends- The game is rebranded. It's all downhill from here. Nothing notable except for a few ships and crew.
Fire and Steel- Includes some powerful stuff like Mycron. Note that the English never get shafted, ever. They have to get something good.
Savage Shores- A small but good set. Has a lot of fun stuff, but is still haunted by rebranding.
So what can we learn? Pretty much everything after SCS went sort of downhill for me as I'm not too interested in Fantasy.
The other problem was power. In a response to Rev, the designers swung the pendulum pretty darn hard towards underpowered stuff.
Another lesson? Don't swing the pendulum hard, look at and address the problems and deal with them.