Making a watch is not that difficult. Plenty of manufacturers have shown that they can deliver a good quality, mechanical watch, and not only in Switzerland. Germany, the US, Russia, and of course the Far East, with Japan in the lead, prove this point. But as always the devil is in the details.
While many of these watches can tell time with a reasonable amount of accuracy, making them even more accurate, will require an exponentially greater investment in knowledge and machines. The same goes when making them smaller, or thinner, or better decorated.
These are also often the criteria that set apart Haute Horlogerie watches from its much less expensive siblings. It also answers at least part of, the question why Haute Horlogerie watches carry a different price tag. A good example of this is black polishing, in which a steel part is giving such a smooth and perfect finish that from certain angles, it looks pitch black. This is not only extremely time-consuming, but it also requires the hand of a master, and to become such a master requires an almost spiritual dedication.
While some decorations do have a function, for example, blueing prevents oxidation of the part, many of them are only employed to make the watch visual more pleasing. Compare it to the effort exotic car manufacturers go through these days to make the engine bay great to look at. It are these details that greatly influence how you experience the product, car or watch alike. While they all serve the same basic purpose, regardless of their price, it are the details that make them either a modest timekeeper, or a proud member of the Haute Horlogerie, which is essentially nothing less then a work of art!