I know it's been 80 years since WW2 but it seems a lot of people have forgotten the main reason for the creation of EU. The EU was created in order is to avoid wars in Europe. It might sound ridiculous to many, but Europe used to have A LOT of wars in the past.
Economic criteria, corruption, etc are all great metrics but in the end, it is about avoiding wars. And a Ukraine inside the EU means a safer EU, a safer Ukraine and even a safer Russia. Russia wont be able to go full retard and Ukraine would have to compromise and reach some peace agreement in order to join the EU.
Inclusivity is very important for the EU. Reminder that even Russia could join the EU but a country like Russia, which sees itself as a super power, wouldnt want to be the 5th-6th most important member of the EU(in economic terms).