They probably blew all their creative efforts on those two songs, and filled up the rest of the album with whatever was coming out.
They said in interviews that they were suggested to do a Keeper album, 'cause the lineup was strong enough to afford it, maybe they decided they needed big epics to be worthy of the title, wrote those, saw that they were good, and didn't bother to painstakingly creating other masterpieces.
It's still a good and consistent album, and they were smart enough to NOT call it Keeper III, but they should have just avoided the Keeper part in the title and just let the songs tied to the saga speak for themselves.