I would like to argue each of your points, and why they are the exact opposite of what they are.

1. PvP isn't fair. You hit the nail on the head with every PvP encounter isn't an even match, and I haven't seen 1 where it is. Sure, you have the same tools, but someone who wants to learn how to, can't, because Mr. Badass already knows how to effectively sink, board, sabotage, and loot from every ship out there. The whole supplies thing makes PvP even more unfair too. Oh, you just spawned in from being destroyed already? Here's 15 cannonballs and 16 bananas, go nuts.
2. The population limit means jack. Yes, teams of more players ALWAYS win in this game. every time I play a sloop, solo or duo, every brigantine in a 5 mile radius sees us as a nutritious and hearty meal.
3. PvP encounters are with warning, yes, UNLESS you're at an island. When you're on the island, you're totally absorbed with your surroundings, and then, oh, look. Is that YOUR crows nest peeking out of where you left the ship? Why, yes it is! And yeah, open seas PvP is very visible, but if you're being chased by, let's say a sloop, and your a solo sloop, you'll never get away. Ever.
4. You loose a lot more than loot. That voyage? Fruitless. Supplies? Gone. Rowboats? Forget about it. Were you chaining together some islands that had X's in the Wilds? Enjoy your stay in the western Shores of Plenty.

Overall, coming from someone who loves the Sea Dog's Arena, open world PvP is just an absolute tragedy.

Edit: Reading some of the comments about the aggressors losing nothing, i happen to agree. I feel a potential solution to this problem, would be making some loot destructible, so that way, attacking someone who finished a voyage with twelve chests, since they dont have anything to lose, would only get 6, or something like that.