I don't care to speculate about this either way, though I also don't have a problem if they do. (Some of the older packs, like GT and GTW, could use some more updates if you ask me.) But I'm gonna go ahead and mention that comparing previous releases in the series, such as from Sims 3, to current ones, is pointless.
The gurus have said many times there is no continual pattern from the past that they're going on this time around. Saying Sims 3 Pets had this, that and the other thing is irrelevant. Sims 4 has Cats & Dogs, and now this new pet pack too, not a Pets EP, and it wasn't intended as such. That's not to say you can't feel this new pack was somehow supposed to be with Cats & Dogs (I don't share that opinion but you're welcome to it), but C&D was never meant to be all inclusive to every pet regardless.
