Ask HN: Why is Riak support mostly missing from Apache's big data ecosystem?

I've been investigating Riak to do data analytics and I'm kind of baffled at how few support there is for it in the whole Apache Big Data ecosystem.

The only thing I can find is Basho's own Spark add on.

Why? Is Cassandra really better for the generic data analysis use case? Or is just the default and it is not well perceived within Apache to add support for 'outsiders'?

I'll likely commit to Apache tools for the analytics, and am worried to have to bake many times things on my own with riak.