Data integration is critical for Power BI consulting services because organizations often pull data from multiple sources. Effective consultants use Power Query and other ETL tools to clean, transform, and merge data from disparate systems into one cohesive model. Ensuring seamless integration helps businesses make use of all their data, regardless of its original format or location. Successful data integration allows for better insights, reduces manual data handling, and enables comprehensive analysis, making Power BI a more powerful tool for organizations.