What I like about Sims 4 is the general look and feel of it. Its graphics are far better than where I began with Sims 2. I love the new CAS and how we can push and pull until the Sim has the basic body shape we desire. I'm still trying to master the faces, but I will get there. I love the build mode, too. It has a mean learning-curve, but I have what I feel are glorious builds I managed to create. Sometimes, even the harder ones that give you floorplans from a magazine designed by high-ranking Architects, modified ever so slightly to be playable in the game. Nothing more satisfying that getting it to a point where I love it myself. (Perfectionist, learning how not to be.)
I use mods and that has opened a whole new game for me. I loved having a singer Sim and missed that so much. Then we got Get Famous, and a modder created the Road to Fame mod, Professional Singer Career, which has been further upgraded as time went on. My Teen Sim is now a Global Superstar, has won three Best Song Starlight Accolades and summer vacation isn't even over yet. One more week of high school and it's off to Uni with him.
Like the OP, if this was goal-oriented I'd be bored out of my mind. I love being able to direct my own 'show' so to speak. I play on Long and set aging off when the YAs go off to Uni. Sandbox suits me very well. I do hope it can stay this way.
With the changes to the neighborhood, Llamas, cows and chickens in the game I'm very excited for the future of Sims 4.