I am Turkish and I feel like the culture difference is just too massive to be a member of EU right now. Economically, it would be an nice addition to EU, because Germany and France would very much enjoy the free access to the this huge market, so the current situation reflects that: EU has nice access to Turkish market with the current agreements, but they do not allow Turkey to be a member.
would you say the cultural difference was equally massive 20 years ago, when turkey was much more aligned towards an EU future? I don't think so much has changed in turkey culturally, but a lot has changed politically
No, I still think we were not ready 20 years ago and we still not are. The main problem with the political changes that it stole from the time we could have used to find a middle ground between both cultures and be compatible, but it was spent on nonconstructive things instead. I do not support that Turkish culture should be replaced by European one, but we could have made it work somehow.
Growth is irrelevant unless you're a net-contributor. The EU really doesn't need more underdeveloped economies to support, it needs to get everybody to a similar level and deal with the tax havens, not do some SV-hypergrowth model where the issues will magically resolve themselves if only you can have 15% population growth by acquiring more members.
Yes, and that's great for China. But for a country to benefit the EU by becoming a member, it would have to be above EU average and be a net-contributor. Turkey isn't anywhere close, so it would be another money sink for the EU.
It's not that simple. You'll want to look at GDP/capita to compare countries in general.
My point is a different one though: If Turkey joined the EU, it wouldn't be a net contributor, it would get huge subsidies from the EU. As such, it wouldn't benefit the EU economically, and it would be a disaster politically. It may be nice for some private companies to get easier access to a new market, but the price would be much too high, and I'm fairly certain that the EU would not survive Turkey as a member state.