Germany also buys Russian gas. It's basically the last thing Russia has to lose anymore. If they escalate the conflict even more (by even more brutally bombing civilians) I'd be surprised if energy was not part of the sanctions.
In essence it is to maintain some leverage, on top of the usual practical and selfish reasons.
In addition Americans are notoriously sensitive to the price of gas (in a similar vein the joke goes that Russia has had two price spikes in Vodka, first in 1917 and second in 1991, maybe we'll get third one soon). If it rises too much they might start to oppose the whole being uppity to Russians thing going on now, which would be bad.
In essence it is to maintain some leverage, on top of the usual practical and selfish reasons.
In addition Americans are notoriously sensitive to the price of gas (in a similar vein the joke goes that Russia has had two price spikes in Vodka, first in 1917 and second in 1991, maybe we'll get third one soon). If it rises too much they might start to oppose the whole being uppity to Russians thing going on now, which would be bad.