I do think a habits system would be pretty cool. Like brushing their teeth, putting away leftovers. My children and teens often set the table, and if they get the manners trait (Or is it responsible? Many of my sims have both, so I'm not 100 on which) they will auto set the table as an adult.
I wouldn't like my sims to auto walk the dog. That is a long action and I much prefer to do that on my own schedule. Now, if it was a very well programmed habit system, such as it learned what you have established and it went off that to form the habit - such as walking the dog as soon as my sim returns home from work, or as soon as they shower first thing in the morning - then, maybe.
But, at that point, I will still have to sit there, while they do it, so really I only saved myself one click to have my sim auto do it. And that would require a pretty advanced system that I'm not sure EA/Maxis is likely to invest in this game. I love this game, and I love the guru's, but half-baked has been the theme since the beginning of Sims 4, I can't see them suddenly getting the budget allowed to really dig in deep for a habit system. We can't even get favorites, at this point.