“Many UX vendors are intent on just doing the projects. They don’t focus on helping internal staff to learn UX skills or building a UX infrastructure for their clients. Some even try to hide their practices. Get a vendor who is on your side in building internal knowledge and capabilities. Get a vendor who will work itself out of a job.”
When 97% of companies have “good customer experience” as a strategic imperative, you might want to get a vendor who is focused on world class experience engineering.
It might be because you want to get a project done and get the benefits of good UX for that design. It might be that you are starting up an internal UX practice, and you want to make sure it is an effective operation from the start. It might be that you have an established and mature UX practice and you want to support that organization with focused training, tools, or staffing.
Someday, UX engineering will be baked into every system integrator’s practice. And someday every organization will have an internal UX team — if you just rely on vendors, it won’t work. “Quality” has gone that path. And so will UX. But today, if you want really strong UX, you will probably need a UX-focused vendor.