reasons to spay inside only cat?

i grew up with inside/outside cats and my first cat was indoor/outdoor when i was in college, (then fully indoors after), so i see the point in getting them spayed. they were all spayed at around 4 months. i’ve only ever owned female kittens and we never had surprise kitten litters.

my new kitten now lives in an apartment exclusively inside with no other animals. i am not considering a second cat and i do not have any roommates.

of course spaying kittens and cats that go outside is important to keep feral populations down, and when I was in college and my cat was indoor/outdoor i did not want to have to deal with kittens.

since learning more about the dangers of indoor/outdoor cats for themselves and the environment my plan is for my new kitten to always be an indoor cat. i also do not want to live in a multi cat household unless necessary. that being said, why should i get her spayed? are there any benefits to getting a female kitten spayed if she will never be around a male kitten?

i feel that its slightly cruel to put my little girl into a procedure that could be entirely unnecessary.