The reason is because the UW one feels like the default commander and White makes Allies the best for waterbending purposes, but Black offers some really powerful waterbending spells and more Clues for waterbending purposes
If you would get a +1/+1 counter and choose to apply Pir first, you'd get two counters, which then gets doubled to 4 by Doubling Season
This is downright nasty in decks with newly unblockable Commanders led by Rogue's Passage and Sun Quan or with unblockable or evasion themselves (Dromar, the Banisher
Not for the player-- getting this good boy down as quickly as possible should be priority number one
another big influencing factor is if you're playing with sideboards or not - in a 8 man draft with sideboarding i'm always going to be looking to pick up a disenchant effect but in a 1/3 cube 2 deck sealed we don't play with sideboards so the disenchant effects are usually not maindeck worthy and just dead weight
Presented in two different timelines, one where all the Dragons of Tarkir were wiped out and one where they lived on and conquered the Plane, Zurgo is an excellent example of the classic nature vs