In order to narrow down the possibilities, let's focus on heptatonic scales with only whole and half tone steps. As a second restriction, let's agree that we don't want two consecutive half steps in our scales. These restrictions might seem arbitrary, but they are quite reasonable from a melodic and harmonic standpoint (for western ears, at least).
Apart from the modes in your question, it might surprise you that, given above restrictions, there is only one more 7-note scale (and its modes) that has a different pattern of whole and half steps: the melodic minor scale. In that scale the two half steps are separated by only one whole step. The modes of melodic minor are used a lot in jazz, so we actually do not exclusively adhere to the church modes.
Note that if we allow two consecutive half steps then there's again only one more scale (and its modes): the Neapolitan major scale. So there are only three systems (i.e., 3x7 = 21 scales) of heptatonic scales with only whole tone and half tone steps: the major scale and its modes, the melodic minor scale and its modes, and the Neapolitan major scale and its modes. All other scales either have at least one interval that is neither a half step nor a whole step, or they have more or less than seven notes (like the pentatonic minor and major scales, the whole tone scale, the diminished scales, bebop scales, etc.).
If you really want to go crazy, you should consider leaving the heptatonic scale system in 12-TET and look for new sounds in different temperaments.