Agreed. Out of the box none of the other storage systems actually allow you to not worry about range scans at all. While HBase will repartition your data to balance the used disk space automatically, in most other systems you'll end up having to manually partition your data in different ways and then aggregate the queries across partitions.

This is pretty literally the main reason why many companies use HBase. Then in the same companies you can also find a good usage for Cassandra but it'd be a different use case.