Although Rashi says that Tamim and Tzadik are two different qualities, we can perhaps also say that Tzadik and Tamim are the same. Like the Meforshim say that the Baal Bitachon is the real Tzadik, especially if: עיקר נתינת התורה בטחון the Torah was given to us mainly so that we should achieve the Midda of Bitachon and in the Tefila of: על הצדיקים it says: וְתֵן שָׂכָר טוֹב לְכָל הַבּוֹטְחִים בְּשִׁמְךָ בֶּאֱמֶת “give a good reward to those who have Bitachon”, which seems to consider Bitachon THE Tzidkus of a Tzadik. And the Medrash says that one day Gan Eden will scream give me only Tzaddikim. Which Tzaddikim? The Bitachon kind of Tzadik.
This is the Baal Bitachon who isn’t a sneaky Ganav. He’s a Tamim who appreciates whatever Hashem gives him, including his nature, and his particular Madrega of Avodas Hashem. He is a true Sameach B'chelko, and for good reason we can say that this is why it says: בְּדֹרֹתָיו in his generation; i.e., Noach was a contrast to his conniving and tricky Dor (וַתִּמָּלֵא הָאָרֶץ חָמָס). Also, אֶת הָאֱלֹקִים הִתְהַלֶּךְ נֹחַ (Noach walked with Hashem) also means Bitachon; being connected to Hashem.
Now we understand why the Torah elaborates on this Midda of Temimus, since it is Ikar Ikarim. Look how Eisav was: צַיִד בְּפִיו cunning and he fooled his father, while Yaakov was an: אִישׁ תָּם Ish Tam, and: יֹשֵׁב אֹהָלִים means staying home, unlike Eisav the Ish Sa'deh who looks for new ideas and tricks. וְהַנָּחָשׁ הָיָה עָרוּם בראשית ג א the snake was sneaky and cunning. The beginning of all evil is being smart and tricky and not having Bitachon in Hashem.
The true Tzadik spends a lifetime working on Sameach B'chelko, happy with everything he has, including all his shortcomings (even in Ruchaniyus). The more you work on Sameach B'chelko, the bigger Tzadik you are. All the Tzaros come from those who are always kvetching, albeit in Ruchaniyus. In the end of every Korban Tamid, they would pour wine on the Mizbeach. The Levi'im would play music on the 3 steps called the “Duchan”.
However, by the Simchas Bais HaSho'eva on Sukkos, the Levi'im were on 15 steps, which are called “Maalos” (going up). Also, only Chasidim and Anshei Ma'aseh danced in the middl. It was an unusual Simcha, וְכָל מִי שֶׁלֹּא רָאָה שִׂמְחַת בֵּית הַשּׁוֹאֵבָה, לֹא רָאָה שִׂמְחָה מִיָּמָיו unlike any other. We can suggest that being happy with pouring “simple” water is a much higher Madrega, which is appropriate for Chasidim and Anshei Ma'aseh. It says: וְיַיִן יְשַׂמַּח לְבַב אֱנוֹשׁ תהלים קד טו wine is there to make people happy, and being happy with wine isn’t such an unusual Madrega, since that’s exactly what wine is supposed to do.
But being happy and making a shpiel out of plain water takes a big Adam Gadol. Now we know why they are called Maalos, an expression of going “upwards”, and why only Chasidim and Anshei Ma'aseh would dance in the middle. And normally there were not as many steps, and why there was super Simcha like only Tzadikim have, since they have a much bigger Gan Eden.
We can also ask, why when we need water and rain (since: בְּחַג נִדּוֹנִין עַל הַמָּיִם משנה ר"ה א ב on Sukkos we are judged regarding the water of the coming year) do we pour water on the Mizbeach, and use Arba Minim which are: גְּדֵלִים עַל כָּל מַיִם especially dependent on water. What does that have to do with attaining water for the coming year? We can suggest, that when a person wants something from Hashem, the way to get it is to show appreciation for the last time you got it.
When you make a big shpiel out of water with Simchas Bais HaSho'eva, you show that you are: רָאוּי worthy for more water.