When and Why do we Accept or Reject Halachic Precedent?

The Torah, Gd, imposes a heavy duty upon each individual to think for themselves. This duty is enunciated in the Halacha [RaMBaM Mamrim Chapter 2] a BD must rule according to its own understanding of the Law and not defer to the precedent and authority of preceding BD.

I had a discussion with a member of the audience, an enquiring mind, after which he sent me this note.

Thank you for referring me to the Kesef Mishana in regards to decisions of Beis Din. What was interesting though which I had not originally understood from our conversation was that although in theory the Amoraim should have argued with Tanaim based on this Halachah [i.e. just as a BD may not bow to the authority of a preceding BD so too the Sages of the Talmud should not bow to the Sages of the Mishnah] in practise there was a Stimas HaMishna and similarly Stimas HaGemorah that created a cut-off point for the ability to argue on earlier authorities. I guess that also connects to the idea of “if they were like angels, we are like men etc.”
Also interesting to note is the the Taz (Yoreh Deah, 87:4 (seif katan 5) – “sheain beyadi lehakel al mah shehichmir rama – I am unable to be lenient against the ruling of the Rama”. This is only one example of many such expressions throughout the poskim – (particularly the pri megadim I have noticed!) Why did he not use his prerogative to argue?

To which I responded:
I mentioned the KMishna in order to clarify that although the RaMBaM, as you pointed out, refers to Derashos made by the BD and which are to be explained and ruled by every BD according to its understanding, nevertheless the meaning is of course applicable to all interpretations of any BD, and of those who have accomplished the required level of scholarship and expertise.

Based upon this understanding the KMishna asks this question: why do the Amoraim not dispute the Tanaim, and his answer is that it was a voluntary convention that they accepted. I wonder if it was not based upon the same need that empowered R Y HaNasi to commit the TShBPeh to writing, Eis LaAsos LaHaShem.

Why do you think it is related to them being like angels?

Your quotation from the Taz is hardly a proof; he is simply not in a position of authority to create such a Pesak. When he and other Poskim use this expression it is the equivalent of a Maggid Shiur beginning a Shiur with a Yesod from Reb Chaim or whoever, and proceeds to explain the Gemara accordingly. If anyone would dare suggest a different approach he would be made to feel like a heretic. But an argument must stand on its merits not its author’s reputation. That is not to say that a reputation does not carry weight, but it should not be blinding. That type of devotion is disastrous for Torah and Halacha and Jewish life and that was the focus of my Derasha’s message.

BTW, it is worthwhile noting that the Taz does not say that one can not or may not disagree; he just says, that HE is disinclined to disagree with the Rama.
What do you think?