[…] It always comes across to me as Lucas thinking he’s really shown how deep he is. It’s ham-fisted.
I don’t think Lucas was trying to sound deep, all of his dialogues in the PT sound “solemn” (or sometimes cheesy) like that one, it’s just part of his style.
The scene in a nutshell: “Hey, look at how gullible the Senate is to automatically fall for Palpatine’s bullshit, even though he’s provided no evidence to back-up the claims he’s making against the Jedi!” It really drives home how stupid everyone who isn’t Palpatine is in these movies, how none of them can put 2 and 2 together even when the signs are blatantly there in garish neon colours.
The Senate is not really falling for Palpatine’s speech, it’s just colluded with him. The whole scene may seem stupid to some, but I think it should look very familiar to most of us in this forum, because it’s basically what we see every day in our parliaments: Lucas was basically telling us the PT is actually set in our world and that this is the way it could turn out one day.