This is just my comments on the review, please do not take it personally.
First and foremost, I think we need to make clarifications on your story which are the following:
(1) Akito is mostly annoyed at Yurika and Megumi. It MAY be true that Akito probably has a suppressed feeling for Yurika
at the start of the series, but for Megumi, it's mostly a one-sided affair. He would most rather watch Gekiganger,
than to even notice the two of them.
(2) The 3 new pilots are actually part of Nadesico's manifest... and so are their Aestivalis.
(3) They weren't sent into suicide missions as punishment for leaving the Earth without permission. In fact, they
really weren't punished at all... evidently since the Nadesico is part of the Nergal company, and they have
actually made amends with the military. Punishing the Nadesico crew would be violation of their military contracts. And
in regards to the suicide missions, they were sent as back-up to insignificant battles... hardly suicide.
That said, let's go the technical aspects... you shouldn't compare Nadesico (1996) with Gundam Seed (2002) and Samurai Champloo (2004) as these are both newer... unless you would be referring to the Nadesico Prince of Darkness Movie. The technology used in Gundam Seeed and Samurai Champloo were expensive at that time.
I would have to agree with you on the sound aspect of the dialogues... but then again, maybe Akito and Yurika's voices were really supposed to be irritatingly loud.
The musical score on the other hand is a different story. I actually have all the OSTs for Nadesico, and I find them appropriate for the anime and they were terrific. Having two different kinds of anime soundtrack (one for Nadesico, and one for Gekiganger) on one anime is a blast. What better way to enhance the mood of the series than to have Gekiganger 3 Theme music so appropriately tuned to the 70s-80s mecha series? And the Nadesico music ain't so bad either.
I don't think originality should be a problem... after all Nadesico is a parody of a lot of anime... from the 70's mecha (Voltes V, Mazinger-Z), to Macross (Robotech), and even closely venturing to Evangelion. It's supposed to have a lot of borrowed ideas twisted to make it more fun and enjoyable.
I think that it's in Yurika's character to be just overly dense about relationships, and still be a tactical genius... so you're right about that.