JohnRawls wrote:To a degree you are correct but not fully. Countries join the EU because it provides economic prosperity, investment, stable currency and great many other economic benefits at least for the new members. Obvious other advantages are that we can throw our combined wait around for better trade deals and other geopolitical stuff. Being admitted in to the EU is very convinient as a stamp of approval of sorts for some standards: democracy, classic liberal principles(private property, rule of law, etc), fight against corruption etc The downsides is that we have harmonized regulations to a degree and some common policies.
Right now the problems of the EU are structural mostly in which we need reform. We need to reform our decision making apparatus to a degree OR at the least tackle the migration, euro and debt issues separately. This will come in due time. Actually if Russia joins the EU then we might have a counter balance to the French/German interest. A Polish/Russian block would be possible in such case. That is currently just speculation.
As for Russia, well the main benefits of the EU is what Russia desperately needs right now. Life is not going to get better in Russia without those things. Not in a meaningful way at least.
You are talking about corruption, but you apparently forgot that, according to the report of European Commissioner for Domestic Policy Cecilia Malmström, corruption costs the EU economy at least 120,000,000,000 euros annually. The report also notes that insufficient attention is paid to the fight against corruption and this problem is often ignored.