I went back to UMD this past Shabbat and the student who gave the D'var Torah at Shalosh Shiddus asked an important question: "Why in all of the nessim of Chanukah do we commemorate the event by lighting a menorah?" His answer, which came after some proofs, is that by acknowledging a small nes it allows us to appreciate the larger ones more.
Unfortunately I don't know his name, but I think he's right on target.
Rav Shlomo Aviner points out that when there's no Shemen Tahor it is possible to light the menorah with Shemen Tameia. When Rov Am Yisrael is Tamei it is still possible to bring the Korban Pesach and to build the Temple. The same din is applied when there's no Shemen Tahor; it is mutar to light the menorah with Shemen Tameia because it's a communal activity. (Tal Hermon vol. 2 p. 85)
So, if there is the case, why the big deal about finding a flask of pure oil and, more importantly, why did HaShem deem it necessary to make it last for eight days? Rambam tells us that this is how long it takes to produce Shemen Tahor, but why does any of this matter if they can use the Shemen Tameia instead? Why the נס פך השמן?
I think the answer comes back to the student's original question. "Why in all of the nessim of Chanukah do we commemorate the event by lighting a menorah?" It is the seeming triviality of the nes that makes it important. The Jews in the Temple went out of their way to find the Shemen Tahor and their actions were rewarded with a nes.
If this idea is accurate then HaShem davka made the נס פך השמן so that we would appreciate the Chag more. Instead finding us celebrating the נס הניצחון הצבאי in some other way, we are found at home bringing light into the world with our families.
Chag Orim Sameach