Early in the design, we have looked at various modes of proxy deployment and found that there are pros and cons for each. You are right that the sidecar model is not always the optimal choice, it's a trade-off (see the referenced document in the discussion). The sidecar is the least invasive approach with respect to Kubernetes and was the focus for the initial release. We'd be happy to hear arguments for a more centralized proxy model, and if needed invest effort into making it happen.