Yea it's changed alright and not for the better. In my opinion, SD has always been a pay to play place for pheasant hunting. If you like paying to hunt and walking in lines with 12 other yahoos then SD is for you. Sure theres a few public places but you know how public places can be. Now with the loss of over a million acres of CRP between North and South Dakotas and the oil BS taking 10s of thousands of more acres out of the game hunting spots are at a premium. If you're dead set on SD, I've done good just hunting around reservoirs. Also the Indian reservations allow hunting, I've never done it but that's an option too.
In my experience, if your looking to just go and knock on doors to get permission then ND was a friendlier place for that, just stay out of the south west corner of the state, it's much like SD there.
Also in western ND is the Little Missouri National Grasslands. Its a beautiful place and holds birds. Pheasants, sharptails and Huns. It's worth checking out.