Taken, and expanded from my answer here:
It says "CHayom Hazeh" and then says "Achar ken"
This "Achar ken", could be referring to the entire previous
statements, or it could be referring to the initial previous
statement.
I think, that in this case, it is referring to the "c'Hayom Hazeh".
The battles before Chanukah, where indeed miraculous, and Hashem gave
a great redemption and salvation, and performed great wonders for the
small Jewish Army.
However, that "Tshuah" and "perkan" did not last very long, and it was
not always clear. The Jewish people were still divided, and needed
allies for foreign nations. It was not until 10-20 years later that
independence was achieved. And then, only 1 to 4 generations later,
sovereignty was lost again.
However, On that day, which we celebrate as "this day", (i.e Chanukah)
is when the Jewish people and leaders felt the victory of few against
the many etc etc, Yeshuah and Pirkan were clear and evident to
everybody, and we pray and give thanks for what "little oil" we were
able to find during those times.
So in short, "k'Hayom Hazeh" means "Like this day (When the victories
were apparent)", which is then contrasted with an "afterward" which
focuses only on the dedication of the Beit Hamikdash and ignore the
battles and hardships that came to the Jewish people aftwards during
that time.
By Purim and Pesach, there was no such "good time/ bad time" dichotomy. After the Story of Purim, the people repented and returned to Israel to build the second temple. After Pesach, we did not go back to Egypt. There is no reason to isolate the miracle of "this day", from the days that surrounded it.
