Why this is important
For common crypto algorithms, it takes a cheap computer to create the encrypted messages and a very powerful (and expensive) computer to break them.
So everyone can create them but only governments can easily crack them.
As computing power gets cheaper, you increase the key length, to keep this state of affairs. If you increase the key length too much so that governments can't crack them, then Joe Public's low powered computer takes too long to create the messages. Hence the compromise.
Now, if you have cheap quantum computers, then it will be as cheap to create and break the algorithms, increasing key length, the same money will do both. And increasing key length no longer keeps the breaking out of reach, unless you make the creating out of reach too.
@cold fusion 2.0
Because, based on this articles (and lots of others), creating a useful quantum computer is now an "engineering problem" i.e. we know the theory and have a proof of concept, we just have to figure out how to build it at a reasonable price. And based on history, throw enough resources at it and these type of problems get solved.
Whereas cold fusion is a "theoretical problem" i.e. it can't be reliably duplicated and we don't know the theory behind it yet.
So quantum computing is several steps further on than cold fusion. And quantum computing will have lots of resources thrown at it, because crypto is (creating and breaking) very important to people with money, as is lots of other problems it can solve (e.g. weather forecasting, logistics)