We have not received permission from Noaani to share the quoted post.
My main doubt with this kind of system would be, in fact, the drama part. If everyone's alerted and "invited" to these bosses and can then sign up to sides - it'd be similar to LFRs and the stuff like that, where solo players wouldn't really need to socialize too much because they could just come to the boss and take a side of the farm party. All while the randomness would kinda defeat the point of guilds being truly prepared for the raid.
If there's, say, 10 potential bosses all across the server and only one of those respawns at random and has 30 minutes of warning - no guild from more than 30 minutes away (which could potentially be ~60% of the server) would be able to attempt the boss. Well, maybe not 30 but 40, but you get the point. And imo that removes the "drama" part of the equation. You can't have drama when it's physically impossible for the guilds to participate in said drama.
In L2 the guild/alliance drama came from guilds partying up exactly because they knew the window of respawn of each particular boss and would be prepared to fight for it on the day. And quite often the alliance between the guild would be kept a secret, so that the opposing force would not bring enough people to the fight. But if your guild from the south part of the western continent partied up with another guild from that region and you wanted to farm a few bosses on your continent and even moved your force to the center of the continent to be able to go anywhere in time - you might get fucked by the rng with several bosses respawning on the other continent. This wouldn't lead to any drama, only to frustration because you couldn't do anything against the rng.
And if you remove the respawn rng, you'd pretty much be inviting everyone on the server to participate in the raid. And, while it might be a cool even in and of itself, the balancing against that kind of zerg would have to be very harsh. Which is exactly why I said that it'd be a nice mechanic for the event bosses. You'd not only have the event itself as the attractor, but also a huge fun pvp fight between all sorts of players.