I think the core gameplay that revolves around errands is just bad game design. The hoops one has to jump through to get autofeeding chickens is absurd, and not worth it. Only the most committed country farmer, with no job, no toddler, and no pressing issues to deal with in the garden will find the time to get 6 animal upgrade parts. So if you just want to reach a point of slightly hassle free chickens, you are railroaded into errands. And those in turn will force you into umpteen other things you didn't want to get involved with, all you wanted was to upgrade a chicken coop that you have in Sulani, for example.
1. I think Cottage Living is too self-contained. It's the new shiny thing now, but when there's something else -- or when you want to do a GTW science career, or any career, or university -- the gameplay of Cottage Living will get dropped almost entirely. Being a lawyer doesn't mesh with doing errands for the mayor of Henford-on-Bagley. I don't want to do errands. I cannot stress how little I want to do multiple fetch quests, involving many differing items and time consuming tasks, for the sake of getting the chickens to not starve. Cottage Living is all-consuming and mutually exclusive of much other gameplay in a way that no other expansion is.
2. I can't think of any item / trait / rare collectible that has any value apart from the Cottage Living gameplay loop. A good example of gameplay done properly is the Unassuming Candy Jar from Paranormal stuff. Every video game is a balance between carrots and sticks: is the grind worth it? In the case of the Unassuming Candy Jar, yes. It's so useful I want it in every save. Other things worth pursuing to me in any save are Laid Back and Sulani Mana from Island Living, maybe computer glasses and the e-sports and Mental Magister traits from DU, the best mountaineering trait from Snowy Escape, Chopstick Savvy and Spice Hound are also nice badges. The GTW scientist career is very worthwhile.
I have a save in the Bramblewood (the Creature Keeper is glitched, constantly trying to plant something that won't germinate) with a golden chicken zapping my plants to perfect quality; I have a giant perfect lettuce... and I don't know why. It seems to have no purpose. Winning at the fair? This is too much busywork for collecting ribbons. There's no meaningful reward from the fair as far as I can tell. The time sink simply isn't worth it to me. In Eco Lifestyle you grind up scrap and make furniture that's actually useful, and it doesn't take so long. Having a lettuce in my fridge for 2 weeks (because the giant veggie fair is a long way in the future, that I probably won't win anyway) seems too futile, too pointless. My sim after a few sim weeks had basically progressed.. nowhere. We don't mind suffering if we're given a reason for our suffering. If the poorly designed game system led to a worthwhile in-game macguffin, I'd do it. But it doesn't seem to. Golden chickens aren't the end goal, they're a means to an end: perfect plants, and perhaps money. But this is already trivially easy for a Sulani Mana sim, and has no downside of cleaning coops or scattering feed. Eco Lifestyle has those incredibly useful vertical planters that can be upgraded to auto-water and spray bugs. So the golden chicken isn't the thing from Cottage Living I need in every save, and I don't think there is such a thing.
I think this pack relies more on the human player finding something cute, but there needs to be a stronger in-game reason to do it. I want the illness curing shower from GTW, it's better when my sims have it. So I do the career. I want the Unassuming Candy Jar, it's better when my sims have it. So I grind for that and give gifts to specters. I myself have no interest in and care nothing for mediums, and I don't think showers that cure disease are realistic either, but it make sense to do it in the videogame. It's fun. And the motivation to go for those things comes from the needs of the sims, the internal logic of the game, not the emotional reaction of the human player. Cottage Living is the reverse. It's playing to me, the human, and to what I find cute... but offers nothing for the sims, no reason for them to do any of it. This is a Problem in a Sims game.
The closest thing to a new, rare thing is the Simple Living lot challenge reward, the Sim Living Cookbook. My sims, well raised as they usually are, can usually max cooking in 2 or 3 dishes. It's already one of the easiest skills. For roleplaying, maybe the cookbook is something to go for. But as a videogame mechanic it fails. The reward is like an end-game sword that kills the weakest enemies in 1 hit... when you can already do that. There's no incentive to pursue it. If it happens, good and well, but maxing cooking has never been a struggle. This is another case of the in-game logic breaking down, appealing to the player to find something cute in our own brains -- not making something appealing or worthwhile for the sim. I think Sims 4 is best at being a video game when we're managing the needs of sims, unlocking things that help them etc., when it's basically the opposite of Cottage Living. I need to feel my sim is doing something that'll benefit him. This will be a minority opinion perhaps, but to me Cottage Living is unequivocally the worst expansion pack.
3. I didn't keep a cow or llama, but ended up with pretty much all varieties of milk and wool anyway, so there's little incentive to have one on my own lot. I never want to keep one, the animals are too needy and it eclipses better gameplay from other packs. Getting a shed or coop to the point they're less needy is also prohibitively tedious. It doesn't make me want to make the effort, it makes me not want Cottage Living animals.
There are new townies to make stories with, and that's fun. I've got an (ever so slightly more regal) cottage for Princess Cordelia on the go. The CAS and build items are well made. But I want no further part of the cows and chickens and errands.
