"Single-issue corporatism voters would have been much better served by a Gore presidency"
You believe that. They didn't. Hence the difference in how votes were cast.
Right or wrong, the Nader voters apparently believed that both parties were far too cozy with corporations. So the choice they had was vote for party A that didn't represent them, vote for party B that didn't represent them, vote for party C that did represent them but didn't have a snowball's chance of winning, or stay home. Any of those choices represented an effective "loss" for the Nader voters. Is it that surprising that some of them chose the "loss" that at least reflected their political beliefs?
To you, the degree of difference between party A and party B is significant. To them, it wasn't. Whether or not that's objectively true is irrelevant. People vote based on their perceptions.