Doubling your Rabbit tokens is a simple but effective way to pull ahead of your opponents and works particularly well with other token producers you might run, like Adeline, Resplendent Cathar
if you control Goblin Electromancer it goes back down to 3
But now a lot of people appreciate it, and they should
Lightning Bolt is reasonably close to Fatal Push in power level, helping to clean up early creatures so you can get your game on, and Cleansing Wildfire is a fine card, but mostly being played as enabler
After Ether's ability resolves, the next instant or sorcery spell you cast that turn will be copied whether or not it has targets and whether or not you spent the mana added by Ether's ability on that spell
At least it can banish itself to protect a Buster Blader monster from any targeted effect