Gas isn't easily shippable like oil. Most of Russia's gas is in Siberia, inaccessible for purposes of shipping to Europe. Ukraine holds the only other gas reserves in Europe other than Russia. Gas supply is inelastic, meaning that even minor competition can lead to a big drop in prices. So yes, Russia "needs" to keep Ukraine out of the European gas market.
Yes, there's an incremental point to be made about the location of the gas reserves.
But to get to the real point here - why do you keep defending the actions of a blatant 19th century-style imperialist bully, as if it's some kind of calm, rational actor?
Then you could perhaps be more precise in your choice of actors here:
In particular -- Russia most certainly does not "need" to dominate its neighbors. It's just what the current regime feels it needs to do to maintain its chances of survival.
You're deeply misreading the English language. When I say "I need my phone" I am obviously not claiming that my phone is necessary for basic survival. There are different levels of need, and there exists a level where Russia (believes it) needs Crimea.
In the case of the United States, it's not appropriate to equate the country with the current regime, since the party in power (Democrat / Republican) changes every few years, and although you may disagree, I do not view the two parties as equivalent or as forming one party.
In the case of Russia, it is completely appropriate to refer to the regime by country name, since Putin has been in power forever.
Anyway, this is a useless tangent. It should by now be clear to you and anyone else reading what I mean, even if it was not initially clear.
