My NPCs are Lame - On Purpose

I'll admit it, my NPCs are lame. They are not memorable, they don't have quirks, they are boring to interact with. While I truly admire DMs who can make their NPCs come alive, it is not a skill I have. I am lousy when it comes to acting or making unique voices. I forget the quirks of an NPC from one night to the next. But part of me doesn't care. Part of me makes my NPCs lame on purpose.

I have always felt that the player characters are the center of an adventure and a campaign. While an interesting NPC can make for a memorable night, it can also detract from the players. There is the obvious mistake of having a favorite NPC do for the PCs instead of letting the PCs do it themselves; wherein the PCs are viewers instead of doers.
There is also the more subtle mistake of an NPC interaction taking an inordinate amount of time from an evenings adventure. If a night turns into "hey, look at this NPC" something has gone wrong. Too often, DMs use interesting NPCs as a form of entertainment  instead of letting the PCs drive the entertainment. It becomes a case of "look at the unique/funny/interesting/amusing NPC and let him entertain you. Your PCs are no longer of interest, look at the NPCs."
Also, to be honest, interesting NPCs are a distraction. Really, who cares if the barkeep talks with a lisp if he says nothing that will get the players into the action. Do the players really need to know that the owner of the general store is addicted to ice cream if it will never have meaning for the PCs? Sure, the mayor likes to wear purple fringed hats with owl feathers in it, but what does that have to do with the PCs?

My basic philosophy is that if the NPC is not an integral part of the adventure, then gloss over that NPC; relegate the NPC to the background. Move onto something that showcases the PCs.

This is not to say there should not be interesting NPCs in a campaign, just that they should not be the focus. Interesting NPCs should be used to shine the spotlight on the PCs. Use a memorable NPC to make the interaction and information that NPC provides for the PCs memorable. When the PCs walk away from an encounter they should remember that something happened to them there, not that there was something unusual about the NPC; the NPC should be secondary to what happened.

I don't make NPCs exciting to show off my acting skills or creativeness. I make NPCs exciting to make what the players are doing more memorable. And thus, the majority of my NPCs are lame.