I'm all for having a goal, and even more so for having SMART ones. I love the sort of goals that involve stages of achievement, meaning you feel yourself making progress towards the bigger objective and it motivates you. I agree that objectives need to be set regularly, to ensure clarity and fulfillment in both your role and sense of self.
What I think REALLY delivers is having a behavioural Focus.
Focussing on your behaviour and how you're going to set about tackling a task is essential. Without that, you've got no map.
It's all well and good to say "I will achieve X Y and blah-de-blah" but this can be a box-ticking exercise and often people choose soft, easily attainable goals. Often too, you get to the next meeting and nobody remembers what they said they'd do.
What's harder is setting yourself a behavioural focus, something that changes the way you work for the better. This may be "I will be more aware of my temper," "I will use my email more effectively", or "I will take more time to plan my working week". All these and the billion other variations you might consider involve a shift in thinking that goes beyond just completing a task, and delivers a real result.
Try setting a behavioural focus when you hold an appraisal. People tend to remember more about how they've said they'll be rather than what they've agreed to do.