According to this there is potentially a really good reason for cold viruses to be around. Never mind the sniffles:

“Viruses are seen as unhealthy organisms, but we have identified a potential way they can be used by the body to fight and destroy disease.”
In the method, the virus is injected into a malignant melanoma, then replicates itself and starts killing the cancer.
Researchers expect the melanoma to shrink within weeks and eventually vanish. At the same time, it is expected the virus will circulate through the body, seeking and destroying other melanoma cells.

Note that an article in The Age says:

Australian researchers are “extremely excited” to have discovered that the bug that causes colds – the coxsackievirus – is an efficient killer of melanoma cells.

Now I don’t know what is different between Australians and the rest of us but in the US coxsackievirus most commonly shows up as Hand, Foot and Mouth disease and infrequently as colds which are most often caused by rhinoviruses.