In my 45-years of 'serious cycling', I've NEVER had a problem with riding a slightly 'too-tall' frame. BIDT, I was 5'8'-1/2" with a 30" inseam and rode a 23" diamond-frame road bike. My fore-aft position (with my long-ish torso) was more of a factor than stand-over height. 21'/54cm felt too 'cramped'. Yes, I can <barely> stand--over my 23" frame, and 'the boys' are a bit compromised if I were to stand with both feet 'flat-footed, but who does that? I've been riding this 'too-tall' frame size for over 47+ years, and that has NEVER been an issue.
Looking back, I suppose I should have gone with a 22"/56cm if one was available, but back then (mid'70S) Fuji did no have that option...
My current road-ridden bikes are still 57-58cm/23"