I'm working in a small development group. We are building and improving our product.
Half a year ago we couldn't think about higher characteristics, such as usability, because we had so many problems with our product. Many bugs, high technical debt, low performance and other problems kept us from being able to focus on usability.
With time we've improved our process substantially. What we've done:
So we are now producing stable, reliable releases. The following quote (paraphrased) describes our current situation:
first - make it work; after that, make it reliable; after that, make it usable
We are geeks, so we can't 'make' a great UI by ourselves. So what should we do? What direction can you recommend? Maybe we should hire Usability experts part-time or full-time? How can we explain the importance of Usability to our stakeholders? How do we convince them that this is useful?
You ask, "How can we explain the importance of Usability to our stakeholders?" but I'm not sure that you yourselves get it!
Interaction design (iD) and usability aren't things that you can tack on to an existing products when the "important" things are done. They should be there from the very first start, preferably done in small iterations with small tests and studies. I'm talking about cheap and dirty iD/usability, stuff like lo-fi prototyping, user testing with just four people, having enough stats to be able to detect user errors and such.
If you don't to iD/usability from the start, you risk ending up with the same crappy product as your competitors and/or providing users with band aids when they need surgery.