I really don't know what the EU and the US are thinking. They just might create a Russia that's self-sufficient, while the EU and the US take on Ukranian debt and inability to use the money they're given wisely.
Russia doesn't have to do that, and they never wanted to in the first place.
Ukraine is (was) quite valuable to Russia as a favored trade partner supplying agricultural products from the West and manufactured goods and raw materials from the East. Russia supplied discounted gas and petro products, credit and tourists.
cutting off Russia will motivate them to build their own manufacturing and agriculture, actually building the Russian economy in the long run.
Ukraine is left with a broken country and stuff they can't sell if it's not broken. The EU profiteers can no longer get gas at a discount to line their own pockets on resale, so now Ukraine is worth much less to them, and any help from the West will come with debt serfdom strings.
Russia still gets Crimea, the navy and the port, which will eventually get back to normal and not yield a dime to Ukraine.