Ultimately, his (Hamilton's) argument boils down to the claim that having Senators query into the background, leanings, tendencies, etc. of judicial candidates will lead them to interject their personal grievances or biases, which leads to malicious attacks and fights. Empirically, this is proven by the current state of affairs in the Senate--the rancor over judicial nominees can be directly traced to the newly active role Senators have been taking in judicial nominations. Hence, Mark argues, Senators should show more deference to the President so that the process becomes more cordial and less polarized (since the president can't polarize himself, leaving it to him ends polarization).
In a way, this is parallel to my generic critique of Democracy. To recap, the "dream" of Democracy, at least for all of us politically attuned folk, is for a nice, deliberative Republic in which all citizens rationally discuss the issues presented, fairly consider opposing views, then faithfully elect similar-minded representatives who will implement these views into law without trying to settle political scores or pander for votes. The reality, as we know, is far different--issues aren't rationally discussed, politicians nakedly pursue personal influence over the national interest, and most citizens are entirely disengaged from the process--stopping only so long to see the latest "Swift Boats" ad. At times, it's enough for the politically aware among us to despair entirely, and say
"Enough! If I was dictator, none of these problems would exist."
And perhaps they wouldn't. A dictatorship of me might (emphasized) be rational, empathetic, deliberative, and open-minded--precisely those characteristics Democracy isn't. It also would be elitist, exclusivist, unaccountable, and wholly illegitimate. So I push my megalomaniac ambitions to the side, and recognize that for all its problems, Democracy remains the best of admittedly flawed options.
I feel roughly the same way about judicial nominations. Presumably, if we lived in some Habermasian utopia where politicians didn't make attacks just for the sake of politics and people could and would have rational political conversations, Mark would not mind Senators chipping in on judicial nominations. Indeed, he might favor it, since it is generally better to get more opinions and perspectives on weighty matters than less. But since we don't live in that world, Mark would argue that we must regrettably abandon that noble dream. This is an understandable reaction, but it is as wrong as the impulse to chuck out democracy because so many of its participants present (to quote Hamilton) "a full display of all the private and party likings and dislikes, partialities and antipathies, attachments and animosities, which are felt by those who compose the assembly." Ultimately, our system is premised on the presentation, analysis, debate, and refutation of a wide range of viewpoints and ideas. It cannot function otherwise, and the convenience (and cordialness) of replacing that debate (the sin qua non of "advise and consent") with an executive "trust me" does not outweigh that value.
What you have to remember about Hamilton is that he was an unabashed advocate for extreme executive power. He did not trust assemblies and he did not trust the people. This view has some merit. But it is not the view either our constitution or our republic has adopted. The proper response to a damaged democratic process is not to abandon the process, it is to commit oneself to healing it. Judicial nominations, like any other policy issue of import and weight, requires a diverse array of voices to be heard. Pluralism is if anything more important in high stakes situations such as this. And so I defend debate--warts and all. There is no other way consistent with our traditions, with our constitution, with our democracy.