The explanation usually offered by those instituting these circuit breakers is that they don't have any problem with people who want to trade at some price eventually trading at that price, they just don't want people to have to trade without thinking it through due to extreme time pressure.

For example, there might be a rumor (perhaps started by an unethical competitor or market manipulator) that Company X was just caught in some sort of scandal. Those who panic most and sell soonest might get a better price than those who take the time to find out the truth, providing a potentially serious financial motivation to panic. Panic, and rapidly falling prices on something large, can cause sales of other assets as a hedge against others selling assets as a hedge...and it can cascade out of all proportion to what is actually happening in the economy.

The idea of the circuit breaker is that it stops everyone from trading but doesn't stop the news or analysis. Let everyone catch up on the news--what's really going on in these companies and their markets--and then let people trade based on facts, not panic. After more is known, and known by all, those who still want to trade will be allowed to do so.

Whether it really works out that way in practice is a different question. A circuit breaker that doesn't stop trading long enough for anyone to learn anything beyond additional rumors might merely allow the panic more time to spread, but the above is the usual explanation given by those who make the policies.