Agreed, I the most fun I had in warmode was at the start of BfA before the meta was to just join a raid group. I think if there were ways to discourage raid groups then world pvp could be fun and as you said it can get laggy with too many people.
BfA also had incentives for world pvp with the meta achievement giving a mount. Shadowlands originally had a Deathbringer mount/title but it was unfortunately removed before launch. I think if there were rewards added back to the world pvp achievements it would help give world pvp a little more life with those incentives.