That's because the game is different in its core.
One raid tier difference is pretty fuckin huge in a version of the game where everything is optimized and classes actually need to press more than 1 button for their rotation.
Especially since you can get as good gear as the one-tier-older raid from world quests.
Classic has no actual thought in it when it comes to design. The developers were new to the MMO genre and made totally random items, most of them so absolutely unusable it makes you think who even had the idea to make them.
In an environment like that it's not easy to find items that are simply better due to their attributes, because there might not even be a choice at all.
Modern WoW has a dozen of dps trinkets each tier. When all those are worse at the highest level of play than one from the previous tier it's a much bigger deal.