@ever-reddy I think this is an interesting question to ask.
I'm one of those who enjoys PvE, I spent a good few years sinking PvE ships in PotCo, so have experienced both.
With Sea of Thieves in particular, I think the argument for addition of PvE vessels would mean not only a greater variety of ships would be possible, but that the world itself would feel less desolate. So for instance you'd see the odd merchant fleet, maybe fishing vessels, perhaps a rogue Spanish treasure ship sailing through the waters. These to my mind, are scenarios that are more easily accomplished using specific NPC/PvE ships.
Given then, that there would be a mix of Pirates as well as the NPC ships, you would still experience that excitement when you saw a flag on the horizon and knew it was another player, but you'd also have the option and opportunity to go after other ships.
I have also played PvP games and really enjoyed the thrill, unpredictability and excitement of encountering other players - but it does come with downsides, as we've seen in the many posts where encounters haven't necessarily been either pleasant, or enjoyable even under the wide umbrella of 'piratey' behaviour.
Everyone will come to Sea of Thieves with their own experiences and preconceptions of how the game might be played, whether you role play, you're out to sink as many other players as possible or you're aiming for Legendary Pirate status. It's when these styles of play clash, I think it might lead to a less than optimal experience, especially when it can also spill over to hot tempered exchanges via messaging etc.
You're dealing with human beings, they're generally going to be unpredictable and as gamers, we already have a good idea of the best and worst possibilities out there, from other pvp games.