I think it was introduced to help with things like lambdas, or other structures that the coder may not know the type of, or it would be difficult to work out the type.

Then the usage of auto was expanded to help when writing generic code.

I think both of these cases are valid uses of auto, but people seem to have run away with it and will literally use it for statements like auto i = 0;

As a professional C++ coder, I personally don't have a problem with auto (or var in C# for that matter) but I'd prefer people use it where it's useful rather than for every little thing.