It's an issue because Labour want to make it one.
They see them as awful for people as it guarantees the person zero income, which makes it hard to plan for a life. On the other hand, the Tories see them as helpful as they allow people a chance to get at least some work rather than claim 100% of the JSA.
No right or wrong answer, it depends on which side of the fence you sit on. Personally I don't see the harm, but I guess if I was reliant on them then it may make it harder for me to start a proper life. Of course, if that were the case I'd go and do something about it like make myself more employable, but some people would rather blame every one else for their problems.