While I can't really disagree with any of the courses on your list, I'll present a contrarian list:
1960: Mauna Kea
1970: Muirfield Village
1980: Shadow Creek
1990: Tobacco Road
2000: Chambers Bay
2010: Memorial Park
Muirfield Village was very influential in making Nicklaus the man, and making ridiculous maintenance standards the goal. If you move back Harbour Town to the 1960's then MV is the right choice for the 1970's.
None of the others on your contrarian list were particularly influential though. What did Chambers Bay influence? Who else has done anything like Tobacco Road?
Tom,
Ted never asked for Influential, he asked for most significant.
Mauna Kea was a construction marvel, demonstrating how completely inhabitable lava rock could be turned into a world class golf course and lead to the boom of destination golf being built on improbable sites across Hawaii and the Caribbean. The significance of Mauna Kea has carried forward through today, with new remote destination resort being constructed in all corners of the globe.
Shadow Creek may be the pinnacle of golf course construction. The product of a blank canvas and a never ending bank account, Shadow Creek showcased what is possible in manmade design and might have been the exclamation point on post war golf course construction. It stands in gross contrast to what was about to come less than a decade later at courses like Sand Hills, Bandon, and the start of the minimalist movement.
The right answer for the 1990 has to be Bandon Dunes, even more than Sand Hills. While Bandon may not exist without Sand Hills, Bandon has had a much greater impact on the game today.
But I proposed Tobacco Road for a few key reasons. I know of no other course in existence in which it is equally referred to it as the hardest course in the world and the most enjoyable course in the world. To create a golf course that polarizing is significant. While the direct ties to Tobacco Road in future work may not be concrete, it seems very clear that Tobacco Road and Strantz has had a significant influence on courses being built today.
Has any other course gone from creation, to hosing a US Am, to hosting a US Open as fast as Chambers Bay? Regardless if you don't think they deserved it, that is significant, especially considering it is a municipal owned property. How many high dollar, high profile private courses were build to host majors and never earned that right?
If you don't think Memorial Park is significant, I won't fight for it. It probably isn't today, but do you think it could be?