And appear like a strong and mighty leader in the May elections. Distract from tanking the economy and encouraging corruption. I could be arrested for saying such things, if I was in Turkey.
Which the US would have been willing to give... if they didn't cozy up to the Russians for S-300 and S-400s.
They also wanted F-35s, not just F-16s. That's not one to sell unless you're 100% confident they won't copy it for their own domestic production, or sell it to, say, the Russians. And modern Turkey is looking a little shaky in that regard (no, not an earthquake joke).
So you are telling Turkey bought s-400 out of nowhere? US never become true ally of Turkey. And your F-35s reasoning is not right as well. From the beginning Turkey is a part of alliance. But now they afraid Turkey to sell f-35 to Russia?
There are other factors for sure, but without Sweden's recent pro kurdish policy swing, my guess is that both Sweden and Finland would have joined today.