Did you ever consider that maybe some of us actually like the way it's laid out by default, and only want to change the color/look? I've tried many "total UI conversions" and none of them proved better or was as well done as the default. You may not like it, but you shouldn't lump all users into the same box as you. Just because we don't all completely change out interface doesn't mean we can't... it just means we don't.
You can twist this in any way. Some say that iOS is more limited, and others say that iOS might not need to be changed. Some say you can do a lot more with Android, others say you HAVE to do more to Android to get it to feel right because most of the stock UIs are terrible. I'm not saying you're wrong, but I can say that using this thread as proof "that iOS customization is much more limited" isn't right. It's just flawed logic and a lack of experience with both sides IMO. Now my experience with Android isn't as broad as iOS, but I do own both and have messed around with both quite a bit.
All I can say is that the different UIs in iOS you see here isn't just for lack of being able to change it, just for different desires and needs. In fact my Android device is layed out almost in the same way because that's how I personally like it.