Go with the Majority opinion in Halacha
In terms of Jewish law (Halacha) we go with the majority opinion. Also we go with the most recent opinion and rely on older ones where no recent ones are available. An example of this is with identifying whether someone is a potential Messiah. As far as I am aware we still hold with the opinions of Maimonides in the Mishneh Torah.
On the other hand, when it comes to metaphysics, angels, etc. there is no one opinion that everyone should follow. Rather opinion varies and has for many centuries. There are numerous differences of opinion between Mainmonides and Nachmanides about whether angels can corporeal or not, whether Abraham was visited by angels or whether it was all a dream. From my understanding one position is not more correct than the other.
My main point being that in Jewish law we go according to majority opinion. This does not apply to Kabbalah (although there are accepted trends such as less focus on Merkabah mysticism and much more on Sefirot and the Tree of Life)
Descent/Ascent of Generations
Related to the above, there is an idea that I have come across on many occasions which is that whilst with regards to Jewish Law our understanding is diminishing in every generation that passes from Mount Sinai to today - the opposite is true in terms of understanding the inner mysteries of the Torah and creation. The Tanach (written law) was canonized at a certain stage in Jewish history followed by the Talmud (oral law) some time later. Since then halachic thinking has adapted in each generation to cope with the challenges of the day.
In the timeline of Kabbalah in Jewish learning there have been several major periods of "flourishing" and innovation (or revelation depending on who you read). The Merkavah mystics were around after and/or during the second temple. At the same time there are such texts as Sefer Yetzirah and Sefer HaRazim. The next period in which much gets written are the Hasidei Ashkenaz in Germany in the 12th century followed by the publication of the Bahir and Zohar in Spain in the next centuries. Then another flourishing in Tzefat in the 16th centruy under Isaac Luria (and many others), followed by the Hassidic movement in the 18th century to the revival today. OK, that is a bit of a potted history but it hopefully illustrates that the evolution of ideas, practices and body of knowledge over time.
So to come back to the original question about why so much focus on Rabbi Isaac Luria and his version of the Tree of Life? I think that it was a pivotal moment when new ideas were disseminated that followed on from the previous big impact moment of the publication of the Zohar. Rabbi Luria held (in my opinion) quite conservative views on practical use of knowledge of Kabbalah and that still resonates with many people today. Depending on what gets taught in schools, homes and yeshivas - those sources influence people's thinking and whilst today I see that Lurianic Kabbalah has a lot of influence, Rabbi Abraham Abulafia and others are "making their presence known on stage" so to speak and I look forward to seeing how trends and practices in Kabbalah evolve and change in my lifetime.
Sorry that was a bit of a rambling reply and in summary my thoughts are:
- In Kabbalah, there is no hard and fast "this is right and that is wrong" only trends that define mainstream thought in each generation
- Each generation has the potential to reveal more of the inner mysteries of the Torah in Kabbalah
- Lurianic Kabbalah has dominated for a number of centuries in some circles but as more manuscripts get published this could well change