In many regards, Snapcaster Mage is actually more powerful than Eternal Witness
In fact, by casting something like EphemerateEphemerate on our beloved MechanozoaMechanozoa, we'll get double its effect as it enters two times, while also cancelling out the downside of the warp cost
Vorinclex, Monstrous Raider and to a lesser extent Carnage Tyrant are better individual cards in the green six department though, so ultimately the question is one of whether youre interested in driving archetypes or more powerful individual cards
Some descend X abilities (like Basking Capybara) are static abilities
The answer is a combination of product strategy and what could be called the lottery ticket effect
Then, unfortunately it gets reach over an evasive ability, so this is probably better on the defense which is also probably why becoming a creature doesnt tap it