Well... in a nutshell, Parks Canada simply hasn't done a great job of keeping up the golf courses under its care (Green Gables, Highlands Links, et al). Moreover, the north shore of PEI is battered by the sea, wind and ice; particularly the north shore dunes, during the winter months. In fact, PEI's government recently put quite a bit of money toward re-establishing/stabilizing the dunes at Crowbush Cove, which were destroyed over recent winters. If this didn't happen, just like Thompson's dunes holes at Green Gables, the seaside holes at Crowbush -- 15 and 16 in particular -- would likely be lost too.
Tom McBroom recently redid Green Gables. I'm interested to see the results.