It remains to be seen if there will be any in-game consequences for any sims caught wearing a slightly-too-informal dress to a formal event, but I hope there will be some flexibility there. It might seem like that's still the case, but players are now able to remove category filters themselves and wear exactly what they want, when they want.
THE SIMS 4 DEMO PLAY MODS
Many outfits were locked to specific categories, and without mods or cheats you were sort of stuck with them that way. Outfits Are No Longer Locked to Categories: Once upon a time (in The Sims 3, anyway) if you wanted a beach-loving sim to stroll around town in a bikini top and a pair of shorts you might have some trouble. That means that if you want to wear a super cute sunhat, you won't have to sacrifice your flowing curls to do so. Hats are finally an accessory that goes over your hair by default, without needing mods or custom accessories.
No More Hat Hair: It's a little thing, but something long overdue. The system isn't perfect, and some alterations (like nose angle) seem arbitrarily placed and hard to find, but the way the cursor changes to indicate what kind of adjustment you're making to an area (scale, position, rotation and so on) is tremendously helpful and makes navigating all the different changeable areas that much easier. Hands-On Editing is (More or Less) as Intuitive as it Looks: It felt so good to look at a sim's face, say "the bridge of her nose isn't quite right" and then be able to reach out and tug it this way and that until it was, rather than wasting time sifting through reams of sliders for the precise ones needed. Overall I'm very happy with the degree of polish that's been put on the next generation of sims without sacrificing their signature look.
Sims are animated and expressive in a way that isn't always easily translated to a realistic style without veering dangerously towards the uncanny valley in my experience. Personally I don't think that realism is the height of game graphics, and stylized looking characters, objects, and environments will always have their place. Many fans want Sims that look more realistic - as realistic as possible - while developers lean more and more into a polished and very animated CG style instead. Sims Look Great: I'll be the first to admit that this is a very subjective point.