I long for a whole 'wild beasts' or 'wilderness' expansion where one can have households of wolves and deer and whatnot, that are under the player's direct control unlike the dogs and cats, and where sims can do nature-related careers and vacations and unlock some way of sneaking in and taking a certain hidden lot, where they can cut trees and build a cabin and become a disturbed hermit.
(There should also be a mechanic where dogs and cats don't automatically follow the sim home from 'wilderness', but only come along if they're next to the sim our you make the sim call them before traveling. A pet left behind would become feral and under the player's direct control like the wild animals. You could then make it trek home to rejoin its original household if you like, or try get by with some 'forage/scavenge/hunt for food' mechanic.
Or you could have the wild beasts come into towns and tip over trash cans and break stuff, or even claim a lot, but they'll always be tense and want to go back to the wild until they raise a tameness skill by being around human sims (who also make them tense). Random sims wandering by will try to shoo wild beasts away from residential/business lots, or follow them around trying to take pictures of them with their phones, and if they can't flee it can make untame/low tameness ones die of tension or embarrassment.
