To an extent, yes, I don't know if difficult is the word because innovative stuff is readily available -- the parks are just so risk averse. It may not be as cost effective on paper in the short term to risk an innovative attraction.
The big parks could buy S&S Axis coasters, RMC T-Rexes, or Mack Xtreme Spinners, they just don't. Instead they put in the reliable but fairly vanilla B&Ms.
The result is that people are pleased but not wowed. "Pleased but not wowed" seems to be the industry trend of the last 15 years or so. By playing it safe the parks actually run the the risk of becoming stale. Innovation was always required in the past rather than optional.