Starcraft 2 Strategy: When you lack larvae, build more Queens

I ran into this in a recent game, and although I lost the ZvZ match to a Roach contain, I found that I had money, but no larvae.  But yet, I need more units.  So, I built Queens!  This allowed me to break the contain, and had I built a ton of Queens earlier, I may not have lost. 

The good things about Queens:

• They can heal
• They damage air and ground (in case your Zerg opponent accidentally rallies Overlords to your base, too)
• They are tough
• They only require minerals to build
• They can spread creep (even ZvZ, this gives you vision and your units really don't perform any better or worse than his)

The bad things about Queens:

• They aren't an attack unit (unless you REALLY spread creep like crazy)
• They consume minerals you should probably be spending on drones or (another) expansion