OK there are a few issues here to address. Firstly a theory is as good as it gets in science and will contain a number of laws within it. A good example are the Einstein's theories of relativity. They will never become laws as such (at least not in the sense it is generally used). So will string theory, quantum theory, relativity theory etc etc ever becomes laws? No not at all and they don't aspire to be so! A theoretical framework should have a number of elements such as predictive power (possibly using laws) and some explanatory powers etc. Now some physicists (and I agree with them here from the little I understand of String 'theory') claim that String Theory is not even a theory, it is a hypothesis. It has not made any measurable predictions as yet (yet!). Until something can be experimentally verified it is not really a theory. By contrast General relativity has been tested again and again and again and has passed muster splendidly. String Theory has yet to do this. It is a very interesting idea and mathematically it is beautiful but we can't set up any experiemnts to test it yet, although there is some progress happening with this at the moment. I'll try to find some links about it. So it is not really a theory yet IMO but it could become one and if it does it will never really move beyond that. Nor will Quantum Theory or Relativity despite being incredibly accurate models of reality (the most accurate we have ever had, far surpassing the physics of Newton and Maxwell etc). Now are more dimensions than three spatial and one time? Is it necessary? Well we don't know but string theory is a good hypothesis for explaining away some problems with modern physics. Unfortunately it seems you need 11 dimensions to make it work. That's just what the maths tells us. Some flavours have even more, some have less but the popular M-Theory has 11. Just the way it works out. It may be that these ideas are totally wrong but we don't know yet. We need to test them experimentally. Finally should we just accept that which seems obvious or 'follow the evidence'? If the maths and the experiments push us to higher dimensions then so be it. We shouldn't dismiss something simply because it seems a bit odd. Relativity is odd, QM is odd but they more or less work. Some people don't accept these ideas for that reason. But I think that is not the way to go about it. So it may be that there are higher dimensions it may be there are not. We don't know if it is necessary until we have further data.

Of course string theory is necessary. Very few things are funnier than string. Life would be very dull and laughless indeed without string.

1-8-2017 Science is in a bad way these days. The academic thing is a closed shop, invitation only, and they don't even like all the people they invite. Science is out, all knowledge is given by centralized authority now. They don't care if you like it or not.