I think its a bit complicated, honestly. There are some games where boss fights are absolutely trite andas the article saysat odds with the game theyre in. However, I also view boss fights and the bosses themselves as integral to a lot of game stories. They add tension to the atmosphere, knowing that everything youre doing is building up to an encounter that you absolutely HAVE to win. It adds conflict because you, as the player, want to overcome this obstacle so you can see the next portion of the story. A villain is only as good as the resolution of said villain.
It adds a roleplaying aspect to a game; You and the character have a similar goal in that singular moment, to overcome and to win against something thats difficult.
Its also a form of catharsis. This asshole has been giving you a hard time and if they just... fell over without any input, I dont see much thats exciting or interesting about that. When I defeat a boss, I feel good about that because I did it. The character wouldnt have overcome that obstacle without me. Its a direct result of my achievement, not the person on the screen.
I think its one of the things that makes storytelling in games fundamentally different from a different medium. Overcoming the evil is dependent on me, not the inevitability that comes with finishing a book or movie. If I can just sit back and watch the Big Bad Evil Guy die, it just means my impact on the story meant absolutely nothing.
For people that watch LPs or watch their friends beat games, I think that achievement is shared. It wasnt written in a script someone won. Cloud beat Sephiroth but I had to make sure he did it and the people watching know that.
A lot of this is hyperbole, but I genuinely think that boss fights in story-based games that have a central conflict that stems from a villain of some sort benefit greatly from boss fights.