As far as I can tell, Queens look like a bad investment over an additional Hatchery:
- 2 Queens costs 300 minerals and consume 4 supply, whereas 1 Hatchery costs 300 minerals and doesn't consume supply.
- 2 Queens require constant management (not too often, not too boring if certain rules are following, but still: they need to be additionally managed).
- 2 Queens allows you to get a +30% larvae output (For 2 hatcheries - it is 2 larvae), whereas an extra hatchery will give you 3 extra larvae...
Now, Queens can also be used as a defensive unit against air invaders, and can be useful as some help against ground invasions... but that is weak benefit.
Could you please describe, why are Queens so popular?