It was so Kirk would have to take an assault team down to the planet, rather than just beaming up the hostages. I can't remember where I read it, but it was in one of the myriad of behind the scenes books that I've read in my lifetime.
I see. So instead of using the familiar trope of something in the planet's atmosphere (or better, a beam-preventing shield like Rura Penthe had) preventing beaming, Shat decides that the entire ship is a dud just to provide the excuse for them to take the shuttlecraft?
That could have easily been edited to something like what happened with the Ent-B (the ship was so new that several systems hadn't been finalized or installed yet):
Kirk: "Why don't we just beam the ambassadors aboard the Enterprise?"
Spock: "We left Earth without several fully functioning systems, Captain, including the transporter. It won't be installed until Tuesday."
Spock stating that line would have been at least twice as funny as Harriman saying it.