The taxes that you pay already are higher than they need to be to deliver the aid they're intended to deliver, because they have to pay for a bureaucracy to assess 'need', check for fraud (more restrictions = more room for fraud = more time/money spent fighting fraud), and even to educate people on the often complex array of benefits available. This system would be much simpler to administrate, there'd be no need to educate people on their available options, and without having to deal with enforced conditions and other eligibility restrictions dealing with fraud would be simpler and cheaper.
The only argument I can see for opposing this is a moral one, that you want to force people to behave in certain ways before you'll assist them. I always find those kind of arguments really skeevy.