The Gemarah (Nedarim 38a) tells us that the original plan of the Ribbono Shel Olam was that Moshe Rabbeinu would only tell the Jewish people the dinim of the Torah but Moshe could reserve the methods of the derivation of the dinim (pilpulah shel Torah) exclusively for his own descendants. However, Moshe Rabbeinu was good-hearted (tov ayin) and therefore shared everything with the Jewish people. The Netziv (in his commentary on the chumash) suggests that this good-hearted act of Moshe Rabbeinu took place at the beginning of chumash Devarim, the month before he passed away.
The Midrash tells us that the Ribbono shel Olam gave the Torah to the Jewish people in the desert instead of in Eretz Yisroel so that no individual shevet would be able to claim that they are the baalei batim over the Torah and should have the final say in psak halacha. Had the Ribbono shel Olam given the Torah to the Jewish people in Eretz Yisroel, the shevet that owned the part of Eretz Yisroel in which it was given would have claimed that they should have the final say. Therefore, the Torah was given in the desert, which did not belong to any of the shevotim, in order that all of the Jewish people would be entitled to an equal say when shailos come up.
It would seem, then, that according to the Netziv's suggestion that Moshe Rabbeinu shared pilpulah shel Torah with everyone at the beginning of chumash Devarim when the Jewish people were located in eiver ha'Yardein, the shevet within whose share of eiver ha'Yardein this took place could claim that they should have the final say in psak halacha. However, the Netziv explains based on midrashim that the particular location in which Moshe Rabbeinu shared pilpula shel Torah with the Jewish people did not belong to any of the shevotim at that time, thus avoiding this problem.
The Gemarah (Eruvin 13) tells us that R' Meir's style of teaching was that he would explain all the logical possibilities in paskening a shaila. In the days of the Tano'im that was not a popular style. Rather, the students preferred to listen to a shiur where the rebbe said what the din is and explained why the din should be so; they were not interested in hearing all the other logical possibilities. As such, many of the students left R' Meir to learn in the yeshivos of the other Tano'im. In the next generation when the Tano'im voted how to pasken l'halacha, R' Meir's opinion was not accepted most of the time because he has fewer students than the others.
We live in a generation where everything is upside down. Most of the students in most of the yeshivos are not at all interested in the bottom line psak halacha, and rather are only interested in the pilpula shel Torah. According to the original plan of the Ribbono shel Olam, the pilpula shel Torah was not going to be transmitted to all of Klal Yisroel. This modern style of emphasizing all the sevoros and all the logical possibilities is really a distortion of the basic mitzvah of talmud Torah. According to the original plan, the ikar of limud ha'Torah was to be the psak halacha le'maaseh regarding every detail of every mitzvah. Our style of emphasizing sevoros in all directions is to be compared to a person only eating a lot of desserts without eating the main nutritious part of the meal. Only after one already thoroughly knows all the data about the chukim and the mishpatim does it make sense to spend time on the pilpula shel Torah.