In a word: yes.
Many apps we use on the iPad started out as iPhone apps. When the iPad was released, the developers moved the app to the iPad - usually by making it universal. However, in a lot of cases, they didn't make it for a rotatable device like the iPad. So, the app is "stuck" in portrait mode ... cause the developer didn't put that function in the app.
So, yeah, we have to live with the app the way it is or see if there is an HD version of the app (HD being code for "made for the iPad at a probably higher price"). Or, contact the developer and see if they ever intend for the app to be used on the iPad in landscape mode.
Marilyn