The big advantage of using OpenTelemetry as the collection structure is that OpenTelemetry is a standardized format for logging, tracing and metrics. With that structure you have the chance to use all tools which support OpenTelemetry to work further with your collected data or to change the location where your logs should be stored.

A second advantage to change to OpenTelemetry structure is that the future way of Microsoft is to lay on OpenTelemetry and to get rid in the future of their own structure. Article described here.

In the end you are collection your logs, traces and metrics in the OpenTelemetry structure and sending them to Application Insights instead of using the Application Insights default structure which is not standardized.