I don't understand baseball fields

I really don't get why is is acceptable to have baseball fields that are all different sizes. I mean sure its the same distance around the plates, but the distances to the outfield wall are all different. It not only effects how easily home runs have to be hit, but also how far the outfielders need to run and throw.

Isn't this like playing football one place and having the field be 100 yards and going somewhere else and having it be 150 or maybe a little wider and somewhere else its 95 and narrow?