It has always been that way since launch. Children and teens have far fewer restrictions than they did in previous games though.
A lot of them are for sensible game play reasons. A teen with ambitious would essentially be subject to perpetual negative moodlets because they can't possible fulfill the needs of that trait, for example. Same thing with non-commital. Childish, as an in game trait, simply allows adults to gain fun from child activities. A child can already do that, so giving them the trait would be redundant. For what it's worth, of the traits listed in the OP, none of them are that useful except for role playing purposes. Romantic is not that great even for Sims with relevant aspirations, because there are better ways to get flirty at the right times. I realize that not everyone chooses traits for pure utilitarian reasons though.
