Obviously, Hashem blesses the year for the “best.” Otherwise, what kind of blessing is it? The word l’tovah is seemingly superfluous. Siach Yitzchak explains that it happens, at times, that the produce is blessed with a high yield, but, regrettably, a shortage of money precludes customers from purchasing their needs. Indeed, it is worse when produce is selling at a low price, but the buyer has no cash, than when the opposite is in effect (the person has money, but there is no produce to be found). We pray to Hashem that food should be available and that people have the funds available to purchase it.
Alternatively, Achas Shoalti says that when the rain descends on an area that is left unplanted, the rain is of little value. Additionally, a blessing turns into a curse when one does not properly avail himself of the blessing. If one allows his material benefits to go to his head the blessing dissipates. Furthermore, one never knows if the blessing he receives is Hashem’s reward to him, and that is all; Nothing else is coming. He has just collected his Heavenly reward; nothing is awaiting him in Paradise.
