Because not every player is about winning all the time. People want to play thematic fellowships like dwarves. I gain a different type of enjoyment from playing thematic fellowships than Madril,
GLR, or Nertea.
Cards that are close to auto-victories against other decks cause NPEs, Negative Play Experiences.
Ulaire Nertea, Dark Horseman is an NPE card.
Sam, Son of Hamfast is an NPE card. Madril is an NPE card.
Galadriel Lady Redeemed is an NPE card.
One Good Turn Deserves Another is an NPE card. All those cards say "I cannot try to win with one half of my deck" in a way that something like
Savagery to Match their Numbers does not. Savagery is more consistently powerful than most of the cards I listed, but it doesn't shut down a side.
Although I greatly appreciate MarcinS and Gemp for making LotR play possible, how I'm still playing 15 years after first release, online play is not the same as in-person. In-person, mature players realized that you had some responsibility for creating a Positive Play Experience for your opponent. Ordinary events were not the place to run NPE decks. Premier events? Sure, all is fair. Otherwise, variety and theme were also praised. Half of all LotR games are lost. Not many store communities were large enough to drive people away - and crushing people with NPE decks drives people away. See, for instance, the pre-errata
The Mirror of Galadriel. Or the introduction of the X-list. There was opposition to both changes; those opponents tended to be more play-to-win players.
I play mostly Tier 1 and Tier 2 decks, but I really have more fun with weaker decks that are more thematic or more puzzling - like
Return to Its Master in Fellowship Block and Southron archery in Movie Block. One reason I don't like post-Movie Block formats is that the site path removed the sense of journey. The game became "Fights around Middle Earth."
I'll turn the question around, particularly for you who routinely play NPE cards - do you gain nothing from thematic builds?