Funnily enough this is likely explained in the same issue of Neil Gaiman's “The Sandman” that explains supermans ultimate origins. (The whole series is worth checking out by the way even if comics books aren't your thing, Gaiman creates terrific stories throughout and there's some really great artwork.) To make a long story (kinda) short in a flashback to what amounts several billion years B.C.E the eponymous sandman, the anthropomorphic personification of dreams, visits the city of stars wherein it is revealed that stars apparently living thinking beings who are capable transmitting their consciousness to a shared environment while maintaining their actual physical locations in space. Alot of things happen while Dream is in the city of stars, including sex between entities who have absolutely no reason to sexually reproduce, and learning that death had an a real ‘I am the inevitable fate of all things’ emo sorta phase before she became the perky goth The Sanman reader’s came to know and love. However, the most important things we learn i in the case of this thread is that stars can somehow guide the evolution of the life that evolves on their orbiting planets. The then teenage star Sol (our sun) had great admiration for the physical beauty of an Oan visitor to the city. This visitor, who is a member of the race of creatures who will eventually become known as the guardians of the galaxy and found the green lantern crop, was a tall willowy humanoid woman and is what Sol decided to base his “design” of humans on. While it isn't stated outright in the comic that the Kryptonian sun (Roa) decided to base the humanoid kryptonians on the Oan’s physical appearance, the Oans are apparently the first intelligent biological life form the evolve in the universe. In another panel Rao can be seen having a conversation with the anthropomorphic personification of despair about creating a race of people on a planet so unstable it will eventually implode upon itself, for the sole purpose of creating a sole survivor of said species who can escape it’s destruction (I.E. Superman). one can hypothesis the humanoid kryptonians (and indeed all humanoid species in the DC Universe) we’re guided to exist by the parent stars of whatever planets they exist based on the way the Oan because she was the new hot item at the time when many of them were deciding what their sapient biological lifeforms should look like. Sort of like who how Paris Hilton became culturally relevant it was suddenly not uncommon for tasteless overprivileged socialites to have dogs they could and would carry in their purses. This is further supported by how she (the Oan not Paris Hilton) was desired not only by Sol but by Dream himself as well as her own Sun .

TLDR: It’s probably because giant balls of space gas think one of green lanterns bosses was extremely banagable, also it’s Superman’s fault his planet blew up.