well if you are going to have them react to someone stealing something, then you need to have them react to any other event that happens locally or even the world. Thats more spoken lines, more scripting, more text that needs to be done. Costs aside theres only so much information DVDs can hold. Now while in your example its jsut one character but multiply that with all the npcs that need to have the same reactionary things done for any and ever interation that can be done that is alot of data to stick on 1 disc.
Oh please, your argument is a fallacy all the way around. It is invalid in the following ways:
1.) It is not an arbitrary NPC. It is a quest-specific NPC reacting to it's one and only quest specific item. One of the very first you meet in the game!
2.) The game doesn't need to reconcile it with more lines of dialog, just take that dialog out! Should the Golden Claw no longer be in his store even after you've recovered it, simply revert back to his normal dialog option, and not "Thaaaaaank yoooooou."
3.) You want to talk about enough data on one disc? Why not pay attention to the more ridiculous issue of the several different voice actors all given the same dialog? The same amount of space Bethesda took to have multiple voice actors do different iterations of "Some call this junk, me, I call it treasure." could have been spent on more dialog variety.
So instead of 20 different guards in Skyrim all having taken an arrow to the knee we could have heard things like,
"Oh, excuse me, I've misplaced my knife."
"Looks like it will rain soon."
"I took an arrow to the elbow."
Yeah, it's inane, but it's more realistic that what the game's already giving us. Space efficiency is clearly no issue with Bethesda.
-My shout has failed to work a few times until after I sheath my weapons
-Characters regularly repeat sentences immediately after finishing them
These are two of the most irritating issues I've had. The first one I know is caused by lag, and the second is the result of a character being allotted the same dialog for when you approach them, as well as when you start speaking to them.
For some reason Vilkas at Ysgramor's Shrine is particularly fond of this, to the point that I just start attacking him after he's reminded me for the third time that he's too much of a dike to even follow me into the dungeon, despite running several miles to get there.
Similar to the first issue, Werewolf howl audio queues are often extremely delayed. The animation will occur and the effect will activate, but the roaring sound can take several seconds to come up. Lagging shouts can be a real [censored], especially on higher difficulties where pushover enemies like Mudcrabs and low-level Bandits can carve you up with a few swings.
"Oh crap, oh crap, oh crap, get away! Take this! FUS RO DAH! I said, FUS RO DAH! Dammit! Why. Won't. You. Shout!? Aura Whisper!? NOOO!!!
Great. I stuttered incoherently, blinded myself, and got killed by a Horker... That's how I want to go out."
Another issue they didn't iron out is that you can't switch Shouts if one's already in the midst of casting. This is particularly noticeable on shouts with a casting delay like Aura Whisper, where you have to wait for the screen to fade out of black before you can switch.