More accurately, 99% of the use cases ES is appropriate for don't need sharding. Every time I've needed to shard ES has been a nightmare bad enough that ES was abandoned.
I had a typical case of ingesting a ton of logs into ES. I needed sharding to keep up with multi-threaded writes while something else is doing intensive search queries. I think sharding was very useful in processing a lot of data efficiently.
Yes, It's marked for Q3 because it's a pretty complex feature. And we had a lot of other features to do at the same time. But the good news is that it's very well advanced and is likely to be released in mid-Q2.
But probably 99% of users using ES don't need sharding.