Because that's what Elastic is positioning Elasticsearch for. If you look at the features being added these last few years, so much is about time series stuff — aggregation, time-based partitioning, warm/cold storage, etc. Relatively little focus on structured search.

Because people like to have everything (logs + metrics) in the same place. And probably Beats makes it easier to just ship everything in Elasticsearch (but of course this doesn't make it good)

When I see a nonzero value in a metric about “things that shouldn’t happen,” the very next thing I’m going to ask for is examples.

It’s generally considered too expensive to derive metrics from logs in this way, but it’d be a killer debugging experience.

I was interviewing earlier this year and saw at least three companies actively planning to migrate from their existing relational databases into Elasticsearch.

It seems to commonly be perceived as a panacea of databases.