Legendary creatures, as a general rule, are more powerful than ordinary creatures and have unique effects to make them stand out, and they are also the focal point of the Commander format
Others might be a little more obscure, or less MTG-focused, but either way there are plenty of avenues to turn your cards into cash
While they would be far less exciting without either one of the life gain or the persist (but still having a 4 life gain) the Finks would still be a cube worthy powerful monster
The primary takeaway here, for me, is that Kaseto was a more successful implementation of what the previously discussed Karlov of the Ghost Council, a commander that really cracks open a new archetype and wants its own deck
Over the years, Magics design philosophy evolved, and creatures came into fashion, including even, eventually, in Vintage