In my experience, usefulness of style guide / UI component documentation will hinge on a number of factors:
- Size of your development and design organizations
- Number of web-based products they build and support
- Diversity of designs required for these products
- How centralized or de-centralized product development teams are. (Governance model)
- Quality of development team, turnover rate, and offshore
Something like the Lightning Design system can bring tremendous benefits. It is great for organizations that need to support large, but few applications-based tools, has large number of development staff spread across multiple time zones, low designer-to-developer ratio, and tight, centralized governance model.
I work for a Fortune 50 company and manage something similar for our internal applications, and I would find the Lightning Design system too restrictive. It is heavy and too much to take in for building smaller applications quickly.
So we built a system that does the following:
Gets the product, design, and development team up-and-running quickly without reinventing wheels.
Enforce consistency in design and coding patterns, but not slavishly so.
Allow applications that use the patterns to 'lag' behind, and not break when there is significant update to the patterns.
Built in allowance for design and development team to customize if the project requires it.
We built a two-tier system: Global level + App level. The global level styles and components are light, and contain just basic things like form layouts, grid (optional), header, paragraph, base tables, etc. App level styles and components have more specificity, and can differ from project to project. This structure allows teams to be not 'stuck' with globally mandated patterns for everything. Instead, they can pick and choose best patterns from library from other applications, or create a new one. (most end up doing former).
Flexibility is key. Unless it's the CEO/CIO/CTO directly maintaining and enforcing the standards and patterns, not everyone is going to be happy with them. So to drive adoption and remove reservation, having a flexible system with governance model is key. Start small and scale up.