Thanks guys. The link has some very useful features.
I know that Android is fully customizable. I can do what I asked on this thread by using WidgetLocker Lockscreen with NiLS. That's why I choosed Android instead of Windows or iOS.
I just don't get why the default lockscreen doesn't do that already. Is that so hard to do? The same with the default laucher. Why can't it count the missing notifications for all aps? These are, for me, the only aspects where Android is behind iOS.