Why not? They seem to be doing a good job manufacturing Apple products, which isn't an easy task.
Wait before you judge
What evidence is there to suggest that they cannot?
Sounds as naive a presumption as somebody in the last decade saying: "Why on Earth would Apple, a company who do nothing but build computers, think they can take over the music industry and make phones"
They have their own TV sets, running their own firmware. Works very well too. They have also built TV's and written firmware for others for years. Same goes for monitors and other related products. They do a fair amount of 'off brand' stuff, most of which they do the firmware for.
Why on earth would you assume a company with all their money and manpower wont be able to setup a dedicated software division
Simple. They can hire people who can write software. Well, that's what most companies do to get software written..
I company of that size almost certainly has huge group of software developers already in place wring software for internal use. In fact I'd say most software developers work for internal departments like that. They might already employ 1,000 developers who write software for all those machines and accounting and reporting.
Foxxcon might market their internal software to other manufactures not to consumers. We don't know.
Why do you think it's so hard?
Hey bro, as long as they don't hire someone like Forstall, they'll be fine.
Yeah, because we don't want those Chinese to get all uppity there.
It's called moving up the ladder to take your lucrative job. When Samsung started, they made mostly off label electronic components for other companies like IC chips, RAM and capacitors. They're now a pretty big company.
I'm not judging, I'm... doubting, a little bit.
Because creating good apps and producing vast amounts of hardware cheaply require different mindsets, I'd imagine (I admit I've never tried producing vast amounts of hardware, or consumer grade software, so I could be totally wrong).
The hardware production requires great business management - getting lots of people and facilities, making sure they're all doing their job, working hard, etc. Certainly there must be some creative thinking involved in getting the best processes in place, although I suspect a lot of the manufacturing process is dictated by the designers.
Writing great apps isn't a problem you can solve by throwing lots of people at it. Certainly, you can get as many coders as you can hire and get plenty of reasonably, perhaps very, efficient code written quite quickly, but what you need are creative people with the freedom to experiment and the imagination to come up with great stuff. It's a totally different proposition. Certainly, you could hire people to do that, any business could, but it'd just be one business entering a completely different market, basically from scratch - there'd be no synergy.
The example of Samsung kinda supports my view, I think. They the epitome of the let's do everything, throw it at the wall and see what sticks kind of company, both in terms of businesses and features (and even with the features, it tends to be obvious things everyone's already thought of but haven't implemented yet because they don't have a nice way of doing so), and what's the result? Average hardware and below average software. I wouldn't be at all surprised to see Foxconn's effort prove just as uninteresting.
I'm sort of thinking aloud here, be glad to hear reasoning to suggest why I might be wrong.