Just for context, the "problem" they pointed with multiplayer is that "With a day/night cycle it would be messy when the two players are supposed to progress at different pace".
Or something of that sort. I'm paraphrasing a bit the jist of the argument because I can't be bothered to find the actual quote (which was an answer to someone asking for it in an interview, by the way).
And frankly this strikes me as another example of Larian overcomplicating things, because the simple solution about "progressing time at a different pace" would be "DON'T".
- The "background clock" should always be in sync for all the players logged in a game (i.e. if it's 11:03am for the host, the same will be true for everyone).
- When one of the players enters turn-based mode and the "clock" freezes for them (i.e. If it's 11:05am it remains so as long as the turn-based mode lasts. Maybe with a 6-seconds-progression per round if you want to go overkill with the accuracy), it should "freeze" even for other players relatively afar sticking to real-time exploration (i.e. It will remain 11:05am for everyone as long as player X is in turn-based mode).
- "All players would need to agree on doing a long rest" is a bit of a redundant suggestion, since that's ALREADY THE CASE right now.
There, your "design issue" about "asynchronous time" solved entirely by removing the problem without removing the feature of having passing time.
Potential downside? Can't think of much, frankly, but for the sake of argument let's throw in the only plausible one:
"B-but if the players in turn-based mode take a lot of time to end combat, the others would experience longer days in real-time".
Possible answer: "SO FUCKING WHAT?". Who would care, honestly? How would that be any worse than just having your entire game world stuck in a single time window?
Who would prefer to explore a Baldur's Gate (and I mean the actual city now) frozen in eternal midday, without the joy to experience the dusk coming it, the city getting darker, the street lamps turning on etc, etc... just to avoid a trivial, negligible incongruence with the consistency of the clock?
No one in their right mind, that's who.
Well hear me out, my pessimistic prediction is that the city of Baldur's Gate will be under siege and a side effect of that will be some kind of mindflayer induced 'nuclear winter' weather scenario, so the map will be 'dark' in a certain sense and then they will simply go: here, you have what you want, you complained about eternal midsummer-noon, now you have eternal grey of the mindflayer clouds, now stop complaining.
My optimistic - took too much hopium - scenario would be that the revamped animation and lightning means they are seriously considering 2 or 3 different day-time condition thing for release. Maybe the decision makers don't see the need for D/N but some at Larian must be on the pro D/N side as indeed it has been mentioned as a goal of their previous games in the past, so perhaps the D/N thing is one of those final release surprises they're keeping out of EA atm.
Sincerely, I hope it's the case as otherwise it would be really disappointing. I don't say all games need passage of time and day/night differences but a game whose main plot revolves around a time sensitive issue related to a conflict that involves among others the forces of darkness (quite literally, multiple light sensitive races/classes) vs. those of light, not having passage of time or d/n just screams incompetent writers to me.
No one forced them to do it like this, they could've avoided passage of time and need for day/night by simply writing a different story or introduce 'night time' missions and leave the time-sensitivity simply out of it. E.g. First time you see the grove, cinematic starts showing you arriving over far away hills and the sun going down, then the battle is during the night. When battle finishes, you get cinematic of the sun rising above the battlefield and the surviving combatants entering the gates so you arrive at the grove in the day. Similar things could have been implemented all over. I mean if your studio/engine/whatever can't handle water, then don't make a game with a story involving the oceans but with fish walking on land because of 'reasons'.
FYI: I don't want to hate on Larian, there's a lot of good in the game and it will be worth it for me in any case. I just think these are potentially serious design/writing mistakes of which I can't even imagine your average 21 year old literature student would make, so I think it's important to point this out as the studio's own silence and apparent ignoring of this issue suggests they don't think this is a problem at all while it undeniably is an issue. How big of an issue it is might be open to discussion, but the fact that it comes across as very unprofessional can't be denied. Also consider this, you can have the nicest cake there is, with all the icing you want, if the inside is only half baked and there's holes inside, people are going to notice and those 'small' details will have a much higher (negative) impact on the cake evaluation than all the things that are done as they should. Aka no matter how excellent some parts of the whole are, if other parts are subpar, the whole will never be excellent.