While they do similar things and Leaf may appear as a straight upgrade on the surface, they each have their own strengths and weaknesses
I suspect that the upcoming Mythic Championship will change that, however, and well get into the nitty-gritty of that in next weeks column
(TCG Gandora included in picture for size comparison only)
A colorless 3/4 for three is actually still on-curve today, although today, creatures with drawbacks like "sac a land if this leaves play" just don't show up in tournament Magic it's way too easy to get blown out and lose the game as a result
You can see the ramp up in number of cards still in the drafting cube as well as the long old list of other cards retaining cube relevance
I dont want to speculate, but it seems Magics designers might be more Cat people than Dog people, though I could be barking up the wrong tree