I'm not sure anyone is arguing against the latter part of your statement but you as you contradict yourself by arguing that it's a software problem first. AI is a biological, psychological, cog sci, EE/hardware, et al problem because, as you state, understanding how general intelligence works is important--as it is important to know how to build the technology that will run it (ie, possibly the memristor + something else, of course).
Sure you can program some sort of AI, but try doing it at the massively parallel scale of a brain. What I think the memristor opens up is the very ability to do this. I'm not exactly sure how--not sure that anyone does yet--but "in-memory" processing and moving away from the von Neuman (serial) architecture might be a good step as I'm not sure we can easily develop highly parallel software without letting the low-level architectures handle that automatically in more of a stochastic way.