In 1982, Barahona proved that finding the ground state of an Ising model is NP-hard. Later, in 2000, Istrail proved that it is NP-complete. When I look up the citations of these two papers using Google scholar, it appears that the previous and weaker result has 647 citations while on the other hand the more recent and stronger result has 109 citations.
Shouldn't it be the other way round? Isn't a stronger result more useful?