Those things you mentioned are just how Cassandra works. It's a wide-column key/value store and everything is an upsert because that's how the write path is designed, there is no read-then-write (other than LWTs). If you're using an application that expects Cassandra then this is normal so why would Yugabyte change the semantics?

It's true that indexing is unfinished but they've also long been problematic in the CQL data model so Yugabyte is moving faster and actually releasing something for those who can work with it. Cassandra took years to come up with several types of indexes that all have problems and Scylla is overdue by 18 months on their implementation.