I'll give you two reasons: WLWT and WKRC.
Both these channels will not allow Dish to carry the channel without major consessions including carrying the secondary channels. WKRC DT2 is the CinCW and WLWT is has NBC Weather Plus.
I also think that WCPO which is owned by Hearst wants it secondary channel up and I think Hearst wants something else too, but I haven't been able to confirm that.
Finally WXIX 19 for a while had "The Tube" as its DT2 and it wanted that channel carried as well.
The local channels, charged with serving the public in this are are the main obstacle to HD channels in this area via Dish. Cincinnati has been passed over twice in the last 15 months for HD locals.
See ya
Tony