Fiction writers can’t resist drawn out scenes where the protagonist and antagonist duel with words. It’s even better when the antagonist can gloat at capturing the protagonist.
This rarely happens in real life. James Bond and Doctor Who would beh summarily shot immediately after they were captured.
But writers will always find ways for their characters to get captured and taunt each other. It sets up an entertaining story. 
It’s a good thing you abandoned the “badly written,” calumny.
I don’t say that there was never poor writing, mind you, but it’s worth remembering that luminaries like Douglas Adams wrote for the show.
One of my favorites is in Logopolis where there are about two episodes of a convoluted plot by the Master that involves setting a trap resulting in a bunch of TARDISes inside the TARDIS, and the Doctor almost deciding to flood the TARDIS with ocean water to get the Master out. At the end of this subplot, he’s successfully manipulated the Doctor into going to Logopolis - which is exactly what he was planning to do before the Master sprung his plot.
The very best example of obvious padding was in Jon Pertwee’s final story, “Planet of the Spiders,” in which almost an entire episode is taken up with a gigantic extended chase scene, with the Doctor pursuing the villain using an increasingly ridiculous series of motor vehicles, from his vintage roadster to a hovercraft to an autogyro. In the end, the villain escapes anyway. So nothing was achieved, but by golly it filled up screen time!
Plus, Pertwee was an enormous gearhead, and since it was his last story, they indulged him with all those vehicles.