I think a game like this is bound to result in ups and downs in interest level for its players over time - this isn't like a game that you play through until you 'win' or finish the game and then move on to another one.
I have also been setting my characters on a whole lot of 24 hour tasks and have been logging in much less frequently lately, but I wouldn't say I'm bored with the game just because I log in less often. Just did a bit of redesigning of my studio area this morning and have deleted a few unnecessary houses to free up some room for future content. Definitely still looking forward to what's coming next, especially the Halloween event since I haven't been playing during one yet and would love some of that content in my town!