There is one essential argument that I consider being much stronger than all the contra arguments.
To choose whether we as a society have the moral obligation to provide welfare to the needy one needs to use John S. Mill's approach. To decide we need to be in a state during which we do not know anything about our personal circumstances, the so-called veil of ignorance. We do not know whether we are rich or the poorest of the poor, healthy or ill. Placed in such situation everybody would choose a system, which provides the needy with support. Even though they would have to pay for it if they turn out to be rich. Everyone wants to have at least the chance on improvement. If provided with some help the needy may acquire an improvement and become independent of
welfare.
Ideally then a system that provides every member of society with a minimal starting point from which they may work their way up is required. A basic level of support is essential. It would be hard to obtain education if one has to live under a bridge and hunger. Provided with the sine qua non it is possible to reach an independent stage in which one does not require any welfare.
Furthermore it is very idealistic to assume that everybody in today's society is provided with equal opportunities. Not everybody has equal chances to education. Although, if one works from generation to generation, there is a chance to improve gradually. The poorest family is not able to finance their children's education. Here society has the duty to help with their education so that if they work hard they and their children will not be dependant on society but rather support society in its obligations.
Lets consider another example. A person with a job supporting society, for example a surgeon, relies wholly on their body, the surgeons' hand. Surely he provides society not only with his/ her service but also pays taxes. If through some accident this person looses the ability to work in their profession, for instance the surgeon is incapable of operating, he can neither support himself nor society anymore. If now society provides such a person with enough support, e.g. training in another job than he/ she will be able to work and support society again.
In conclusion society welfare distribution needs to be strictly regulated and monitored to prevent misusage. However, society has the duty to provide every member with a chance and the necessary support to become or re-become a person capable to perform all duties and responsibilities to society and therefore to provide welfare.