To begin with, this attitude assumes that if we don't think about our emotional baggage that it will stop having an impact. I don't know about you, but that's not how it works for me.
Leaving behind a lifetime of habit is a process, not an event. And that process may well take up the rest of our lives and remain incomplete when we die. Generally speaking we have to see that we are moving beyond one situation (past) and towards another (future) to stay motivated (now).
So the past is useful because it is only in comparison to our memories that we have a sense of progress (or any change at all for that matter).
Similarly with the future. You are asked to set yourself adrift on the ocean with no destination and let the wind and currents take you where they will. But we know what this lack of purpose and direction looks like. It manifests as dissolution or in wasted, directionless lives. In one of my songs I sing about feeling like "a fish with no tail, eye's wide, no idea where I'm going". I don't sing it, but to me this is terrifying. This is Hamlet, watching helplessly as inevitability crushes him. Fuck that!
While it is certainly a good idea to focus on the task at hand, for many reasons one has to keep one foot in the past and an eye on the future. Tasks are more enjoyable if we are focused (now), but they are more meaningful if they take us toward a definite goal (future) and more satisfying if we have a sense of progress (past). And if that goal benefits the community then so much the better for us. When we contribute to something bigger than ourselves (society, basically) it is about the most meaningful thing we can do.
Most of the important things in life are complex and difficult and therefore require persistence over days, months, and years. Bigger goals cannot be achieved without a clear sense of direction or a sense of progress as one proceeds.
Without the future we have no sense of the meaning of our actions. Without the past we have no sense of progress. So whatever you do, do not lose sight of either.
*I took my title from a TED talk by Carol Dweck.
But I was also thinking about a Sanskrit phrase which translates as "future, past, and present buddhas" (atītānāgatapratyutpannā buddhāḥ). Chinese Buddhists routinely translated this as 三世諸佛 "all buddhas of the three times", a phrase which is never used in Sanskrit (with one exception). Then, when the Heart Sutra was translated back into Sanskrit, the phrase was literally rendered as "all buddhas of the three times" (tryadhvavyavasthitāḥ sarvabuddhāḥ) - this is the one exception. This is the smoking gun that tells us that the text could only have been composed in China. Expect a publication on this in due course.