CMORT666 has pegged it pretty close. It was police harassment of open carriers that went a long way towards getting CCW passed in Ohio. I'd encourage you to get your CCW because the whole automobile thing is still illogical in Ohio.

I normally CCW but occasionally OC. Some people recommend that you practice OC in someplace like Wally World. It's easy to blend into a crowd there. I suspect that for new open carriers what initially attracts police attention is the fact that they seem nervous. Then they see that you are carrying a firearm. For even some of the experienced, gun savvy police officers here those two factors combined are likely to peak their interest.