You think a majority is an "artificial threshold"?
What if there were 5 candidates and the one with the most delegates had 22% of the vote? Should he automatically get the nomination?
What if he is in favor of (insert hot button issue here, e.g. gun control, abortion, high tariffs) and 75% of the party is opposed to it? The party should automatically choose the guy who supports something that is abhorrent to the vast majority?
Can you think objectively? Rules are created for the best objective results for the entire party. Not just for one candidate with a personality cult.
There is only one rule. The guy with the most votes is the nominee or your party loses.
The “artificial threshold” of a simple majority of delegates has been used by the Republican Party since its inception in 1854. The alternative has never been a plurality; the only alternative ever used by a major party was the Democrats two-thirds rule, which ended in 1936.