There are plenty of mods that disable NPC dialogue. These mods affect Nazeem, children, Belethor's Assistant, Guards, etc..

There is, however, no mod that disables ALL NPC dialogue after the first introduction.

Example: Belethor - After the first contact with this fella he gives a rather long introduction, followed by more words towards his goods. He should NO LONGER greet you with his introduction every damn time to VISIT HIM! A simple "Welcome back!" should be enough. This should follow all vendors across Skyrim.

Though the most notorious are NPC's that wander roads, towns/villages that constantly tell you the same thing every bloody time you walk past them.

I would create a mod that disables the recurring dialogue if I knew how. I'm hoping someone skilled enough can do this.

The mod should not break any NPC to NPC conversations that may lead to quest opportunities.

As great as the whole Sneak thief! ARROW to the knee, and sweetroll giggles are they do tend to get extremely annoying with every pass by a guard. This must be included as well.

EDIT: Another good example would be Ysolda constantly blabbering about running the Inn someday. After you hear this from her once you should not hear it again each time you walk by.

As if now I'm learning my way with the Kit. Can't imagine why it would be difficult to flag all NPC's with the recurring dialogue, take it out after your first encounter and have them shut up for the rest of the game.

You could do this, but just as a warning, there will be some mods that depend on some of that dialogue to trigger the mod.

Now if you install the only one intro mod, it works great, then later on install a mod that relies on the dialogue that will now not show up you will end up with conflicts. This could be a very useful but very clashy mod.

in fo, npc's were in certain factions (like xyzDialogueFaction) for their dialogue (so they'd only use lines that made some sense in their environment), the dlg was controlled via these factions. if it's similar in ck (not that far myself yet), this would be a bit easier to handle than editing every single npc or conversation line, i guess...