Because it is never possible to be completely prepared for the Giving of the Torah, had God postponed it until people were worthy, the delay would have been endless.
To reach the Giving of the Torah, to arrive at the fiftieth day, is not a matter of simply counting an additional day.
The fiftieth day is an entirely different spiritual dimension, and its significance is that no matter how prepared a person can be, he is never truly prepared.
Similarly, even a thousand generations are not enough for mankind to produce a generation worthy of receiving the Torah.
For all that man makes himself a vessel, he is never a perfect vessel.
Hence, there is no reason for such a length of time, and it deserves to be cut short.
This transition to the Giving of the Torah may be compared to what Maimonides writes regarding the spiritual preparation required to attain prophecy.
He explains that after one fulfills all the prerequisites for becoming a prophet, it is then possible that prophecy will rest upon him.
Nevertheless, it is also possible that after all the preparations that he makes, he still will not attain prophecy.
‘There could be a person who has all the abilities, qualifications, virtues, and special qualities of a prophet – and yet does not become a prophet.
A person can reach only as far as the limit of his capability.
Beyond that, there is a point that only God can cross, and that point is a completely different spiritual dimension.
In the end, prophecy is a gift from above.
—Rabbi Adin Steinsaltz