I would like it if this weren't a dichotomy of diversity or gameplay. My opinion is somewhere in the middle because I think this is a better game with the level of diversity that they have added and I like that the game can clearly be more inclusive. I don't think that the idea of sacrificing diversity for gameplay is a good one at all.
At the same time, I do agree that the game needs more gameplay, more to do, more ways to actually play. There are a lot of different forms of gameplay. Cottage Living's style is one form of that. Personally I really enjoyed Snowy Escape, it has a lot of gameplay whether you are playing with Japanese characters, playing with the very snowy area or just traveling. I had a minor petpeeve that they did not update the cocktail list to have any Asian-inspired cocktails at the bar. This meant that sending my sims to those bars felt exactly like sending them anywhere else. I get that they would probably still have a lot of the drinks from the other worlds but I think it was an oversight.
One of the challenges that I see is that I agree with the comments that a lot of the game has basically been geared to 8 year olds. I think most of the players are teens to adults and the game should reflect that more by making sure to continue to update gameplay for adults. I'm not just talking about WooHoo which they continue to add. (I think they should but I think they need to make the game more grown up in other ways too).
I think it is good that they are adding a lot of cultural stuff and I honestly really enjoy a lot of the cultural packs. I like sending my sims traveling anytime but especially now that we are in a time period in which we are dealing with a public health crisis. I'll admit that it is great to still be able to travel with my sims. That is a form of gameplay and should be kept, but yes, there are a lot of forms of gameplay out there.
The recent discussion from the team this week seemed to indicate that they will add at least 3 new occult forms to TS4. It sounded like they are actually working on fairies, werewolves and zombies. It also sounded like they just aren't ready yet. They were a bit cryptic about adding gameplay as a second priority behind representative game updates. I mean, some of what they are updating is not anything that I personally need like the pre-mades lore update. There are a lot of players who play with the lore more than I do so I am guessing that is for them.
I do think it is a good idea for the community to pressure for more gameplay of different types. That should not be on a backburner.
I will just add that it sounds like there will be a new separate game coming out. If I had to guess, I think it will be a fantasy game of some type. I am actually of the opinion that in the future they might want to split the supernatural and realistic play because then they could release more of both kinds of content. As for TS5, I'm really not sure that I will move on and if I do, I will wait a while - even several years. I do think they are improving TS4 gradually. It does not make sense to abandon it IMO. I have interest in the new engine but I don't think the model of just abruptly starting over is a good one. Likewise, I actually enjoy my game so I will obviously keep playing it.
If they are doing something like a new version of Sims Medieval, I might be interested as long as it isn't all subscription-based or an MMO.