Hey @Almachete87!
This is something that's definitely come up, and one of the game designers recently outlined some of the challenges involved over in a Reddit AMA.
You can check out the full reply here and I've quoted their thoughts below as well, thanks for the feedback!
No current plans for crosshair customization unfortunately. Apex's crosshairs are actually quite complex and technical. They don't just grow and shrink in size due to hipfire spread! They move based on aim point movement due to animation and such, change color and add elements sometimes due to character abilities (pathfinder grapple), fade in and out based on sprinting and ammo, go transparent on and off with ADS and menus, and all sorts of stuff. Building a system such that we can present options for players, preview the results, and hook all that data deep into our crosshair UI script would be a really massive undertaking, and it would make future changes and new crosshair additions way more difficult. It's just not high on the priority list in terms of bang for the buck sadly.
It would be nice, and maybe we can get some smaller scope stuff in like color adjustments, but no promises for now, sorry!