Are there any practical reasons that I'm not aware of?
I think there are a couple of reasons for this:
- Existing convention - most dashboard designs were created back in the days when desktop applications were the most prevalent, so the layout tends to be for wide screens with lots of space.
- Application - a lot of the dashboards are used for complex analysis that involves sitting down and looking through a range of different 'widgets' in order to make a decision so it is not suitable for the mobile type of use cases.
- Design maturity - most of the dashboards are not designed to provide the type of data that allows the user to make decisions at a glance, instead using widgets that provide unnecessary distractions from the actual information. Infographics and Data visualization is a specialized field of design, and many interface designers are simply not knowledgeable enough to come up with suitable solutions.
There may be other reasons but I think big data and business intelligence have not yet moved into a phase where the emphasis is on data presentation and decision making rather than aesthetics. If you look at the scientific field where they have been working with very large/complex datasets for a long time already you'll see many examples of elegant presentation of information for specific or specialized purposes.
As a former scientist now working in UX design, I am still waiting for IT companies to catch up...