My experience with ES has been somewhat mixed, exactly because them trying to do everything at the same time and a lot of the specific things we needed being under documented and involving much more try and error than should be necessary.
I for one welcome more focused products, when the need again arises for something in this space.
Unused classes can be unloaded from RAM and it's like they don't exist. The executable is still huge but lower memory and CPU cache footprint.
ES is truly focusing on metrics and things and does have some features to make those use cases easier that Solr would probably need a lot of configuration/customization for.
So, Solr is about search. ES is about a specific set of use cases that rely very heavily on search.
And Lucidworks Fusion (commercial alternative to ES) is about big data and ML and full multi-tool pipeline on top of Solr.
So that’s where they’ve invested a lot in tooling and visualization.
There is a huge market just by going after that kind of customers.