Why people still think that customization is only backgrounds and alert sounds?
Try using a different keyboard, a different launcher, a different SMS application, a different browser.
This is cutomization, not putting a different ringtone
I think you are confusing customization with hacking. I did my fair share of hacking in the day on XP with reshacker.exe on the DLLs and EXE that made up the shell. I also used alternate launchers and docks etc.. But I would not classify any of that as customization.
You can jailbreak your iOS device if you really want and do all of that stuff but what is the point? You are not really changing the underlying OS and UI functionality. You are putting lipstick on a pig.
At the end of the day, an OS will pass or fail based on its core functionality and what apps are available for it, not how hackable it is. All of the lipstick will not change the core functionality or lack there of of the OS be it XP, iOS or Android.
I don't know about you but I don't spend the majority of my time customizing my OS. I spend the majority of my time using it. If the platform does not have fun apps and games to use on it then it becomes really boring really fast.
If you like that sort of crap instead of actually "using" it with third party apps then more power to you but I think you are a really really small niche.
Maybe as I got older, I lost interest in that sort of crap. Maybe I enjoy actually using the devices and possibly "creating" the customizations my self within the confines of the base install.
In a nutshell, I've been there and done that. It now bores me.