The dock is a charging cradle if nothing else. So if both you and brothers' Switch are dead battery at same time,
and you both want to play Switch multiplayer on TV at same time, you need 2nd dock to recharge other Switch.
Many families also have multiple TVs in their house. If you don't, then just leave 2nd dock in a closet for recharging use.

People hyped up the dock when they thought (based on patent applications) that it would hold 2nd CPU, GPU, RAM.
We now know it holds nothing of the sort, so there is nothing of substance that you are paying for beyond charging cradle.
And like every other electronic device that COULD use the charger of another device, they will be sold with charger included.

Everyone needs more than one dock.

The dock makes it easy to setup in the main room for when everyone in the household wants to play.

Eventually you'll have a Switch for every TV in the house(and more) but until then having a dock for every TV will make life easier.

If I recall correctly, it's all bundled at the moment so you can't buy without it

I would think that it's possible to use multiple devices with one dock as long as Nintendo hasn't done anything to prevent it. Though I doubt we will see a dockless Switch anytime soon.

Switch will come with the dock because it's not a "Switch" without it.

Definitely, even Laura said Nintendo considered to release on launch cheaper version of Switch without Dock and Joy Green, but they didn't because that would make confusion on market (whole Switch concept thing). But definitely I can see it in around 2 years, when market is already aware of Switch they release cheaper Switch version just for handheld gaming, for instance Switch Pocket or something similar.

Well they cant really afford another confusion on launch after Wii U, and Switch that cant be played on TV would definitely make confusion on launch with whole Switch concept. But in around 2 years later when market is already aware of Switch they will most likly  they release cheaper Switch version just for handheld gaming, for instance Switch Pocket or something similar.

Not true, dock has connectors also, HDMI and USB are certain for now. Point is that you cant play on TV without Dock, that is main feature of dock, not charging cradle, you will be able to charge Switch even without dock but you cant play on TV without dock.

I don't know if necessarily believe that. I think what The Switch is offering could be huge depending on the details. The idea of playing on the big screen and then switching to a smaller screen and taking the game with you on the go is revolutionary! I love the idea of taking it with me to work to play on lunch, or while traveling, or waiting at the doctors. Than when you're ready, just pop in back in the dock have it transfer the game back on the big screen and just continue from there...the idea is just awesome. With this idea is can make both the Japanese gamers and the western gamers happy. 

On that Nintendo is also counting. :D

But IMO whats most important is full and undivided (like every time before) Nintendo support and focus one just one platform, that basically means much higher number of Nintendo games and bigger attention to just one console than before.

From standpoint of 3rd party, definitely some multiplatform games now can be more popular on Nintendo console than before because some people will love to play some of those multiplatform games on to go and they cant to that on XB1/PS4 for instance.

That's why I can see The Switch being huge if done right. Can you imagine playing Skyrim on the go or maybe Destiny? Not going to lie, I'm just drooling thinking about the possibilities. 

Laura Dale confirmed you could buy Switch dock seperately on the launch date