Ginger Grant is good with using custom visualizations in Power BI:
Now since Power BI Custom Visualizations are not provided by Microsoft, they feel compelled to give you a warning message letting users know this. Here is the message box you get in Power BI Desktop when using a custom visualization. Notice that I clicked on the check box next to the text Don’t show this dialog again. As Words mean things, checking this box means the warning message never appears again. When you import the visualization into Power BI, no warning messages. Now I can use and propose custom visualizations to clients because they really are neat, and now they contain no warnings. Thanks so much to the Power BI Product team for fixing this major issue.
This is good news.