While I understand it could be frustrating killing ghasts and having their drops fall to the bottom of a cliff, they are very easy to kill and die with 1 hit from an enchanted bow (making them arguably the easiest shrine to clear). You can wait until they are over a bit of land before killing them or use a fishing rod (like we used to back in the day) to pull the ghast closer to you. I can confirm that there are more than 2 Ghast Shrines, giving plenty of options for optimal ghast farming. If we brought all the shrines further inland they would end up grouped together, close to one another, which is something we don't want. As a result, there are no plans to move them at this moment in time, but we will keep an eye on them, specifically the one you mentioned nearest The Dreadfort.