Is upward movement the only movement?

I have a question for Udayan. While it is all fine to witness milestones such 10000, 15000, 20000 and be happy about it, I wonder how wise is it to justify what market does.
Watching and reading CNBC commentators, at times, one gets the feeling that Sensex is their baby. Sensex' upwardly unidirectional movement is the "ONLY" and the "RIGHT" movement. Any downward movement is unjustified and not right.

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CNBC's Udayan Mukherjee says:

"Some believe that the move has been too fast. But it's not too fast - the market does what it needs to."

"And I hope that the regulators don’t get too worried about this because last time when we went to 19,000, they got they worked themselves into a tizzy, saying the market is moving too fast, there’s no too fast in the market. The market does what it has to, just enjoy the ride."
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What is market after all? Market consists of buyers and sellers. And if every one behaved rationally, probably there would be only buyers or only sellers. Unless one of these two behave irrationally, markets wouldn't move the way it does (especially in the recent past). Why else would US stock market have had a bull run preceding the unprecedented fall it had on October 19, 1987? Either the bull run preceding the fall can be justified or the fall post the bull run can be justified. Why do we say then that "the market does what it has to".