For Hakba the single biggest upgrade is Roaming Throne, doubling all of our explore triggers and so many other merfolk triggers it's obscene
For the sake of synergy, we probably want that ability to be very impactful and expensive, or we want a commander to further incentivize the activated abilities were using on our other cards
There are drawbacks to Hypergenesis as well, like needing to fill your deck with super-expensive cards that you aren't going to be able to cast fairly if your opponent can shut down your plan of cascading into Hypergenesis, which is a real risk in a format where Teferi, Time Raveler, Chalice of the Void, and Force of Negation are among the most played cards in the format
The creature is also the source of the damage, so you can use this alongside any Deathtoucher for an easy clear
I expect Get Lost to play a role here as well, especially for control decks to cleanly answer opposing copies of The Wandering Emperor