[avz]

You're making implicit assumption that a new OS must come in with a new ecosystem built from scratch. There is a significant number of standards (e.g. POSIX, ELF, PDF etc) that can help you ensure different levels of interoperability with existing software and data. Implementing such standards lowers the cost of building an ecosystem significantly. Also, with the push to the cloud, fewer applications need to be provided natively.

Driving adoption is a matter for all products in the market, not specific to operating systems. You can make it easier with familiar UI, advertising and bundling your OS with hardware (although that may be anti-competitive practice it seems to be widely accepted where I live).

[pacala]

> Driving adoption is a matter for all products in the market, not specific to operating systems.

It's a matter of degree. To simplify, the costs of switching are linear in the complexity of using the product. I apologize that I don't know how to precisely model human network effects (you need to learn the product from someone) on top of it, but intuitively the societal costs are super-linear.

Computer systems are by far the most complex products human kind has ever produced. Given the simplistic model sketch above, the costs of switching in the computer industry are the highest humanity has ever seen, likely by orders of magnitude. Fun times.

[avz]

Computer systems may be complex, but they're not the most difficult to use. I'd say a lathe for example is harder to use than a smartphone or a PC.

Generally, high complexity of the implementation does not necessarily translate into high complexity of the interface.