@naughtly-keller,
I don't disagree that there is a layer of complexity that can come with elastic depending on your configuration. If you would like, you could log a feature request to have the search libraries that you mentioned reviewed for inclusion into future iterations of FusionAuth. I took a look and they seemed very interesting; I appreciate you mentioning it.
In the meantime, if you haven't yet, you can check out the container repo and its search section. There are some pre-configured search settings to be found there.
https://github.com/FusionAuth/fusionauth-containers/tree/master/kubernetes/services.
We also have a helm repo that has been very active.
https://github.com/FusionAuth/charts
Also, I assume you are running a container orchestration service like K8's but if you are using just docker, then you can run this command and have elastic up and running within a single docker container (related link)
curl -o docker-compose.yml https://raw.githubusercontent.com/FusionAuth/fusionauth-containers/master/docker/fusionauth/docker-compose.yml
&& curl -o .env https://raw.githubusercontent.com/FusionAuth/fusionauth-containers/master/docker/fusionauth/.env
&& docker-compose up
Finally, you can check out the installation guides for additional assistance and context.
ES does give you the benefits of powerful queries that can be run from right within FusionAuth Admin UI or via the API. I have seen firsthand how this can really help you as your Monthly Active Users projects upwards and you have more data to sort and consume.
I hope this helps!
Thanks,
Josh