I think all of us agree that OpenTelemetry's end-goal of making Observability vendor neutral is futuristic and inevitable. We can complain about it being hard to get started, bloated, etc but the value it provides is clear, esp, when you are paying $$$ to a vendor and stuck with it.
OpenStandards also open up a lot of usecases and startups too. SigNoz, TraceTest, TraceLoop, Signadot, all are very interesting projects which OpenTelemetry enabled.
The majority of the problem seems like sentry is not able to provide it's sentry like features by adopting otel. Getting involved at the design phase could have helped shaped the project that could have considered your usecases. The maintainers have never been opposed to such contributions AFAIK.
Regarding, limiting otel just to tracing would not be sufficient today as the teams want a single platform for all observability rather than different tools for different signals.
I have seen hundreds of companies switch to opentelemetry and save costs by being able to choose the best vendor supporting their usecases.
lack of docs, learning curve, etc are just temporary things that can happen with any big project and should be fixed. Also, otel maintainers and teams have always been seeking help in improving docs, showcasing usecases, etc. If everyone cares enough for the bigger picture, the community and existing vendors should get more involved in improving things rather than just complaining.