Because there are many use cases for historical data (algorithms' training or its cross-analysis with other data, for instance), while lots of APIs focus on for

Because there are many use cases for historical data (algorithms' training or its cross-analysis with other data, for instance), while lots of APIs focus on forecasting. Maybe at this point we need more innovation in either the forecasting itself (generally "better" forecasts, especially for industries, and better extreme conditions alerting), or innovative use of historical weather data in other domains.