yup, i feel a greater sense of visual feedback when using the pre-ios7 keyboard as well.
it is the same problem with the toolbar icons as well. i couldn't care less if they were bubbly or flat, but as of right now, you tap on a thin icon, and you will often get zero visual feedback of what you pressed.
in safari on the iPhone, try tapping the area between the bookmarks and tabs button. neither button will show any sort of down state, but it will randomly trigger one of the two. wasn't the one you intended? both have "done" buttons, but they are at OPPOSITE ENDS of the screen.
and apple knows that its a problem. in the initial ios7 release, changing the wallpaper on the iPad was ridiculous. when telling it to "set" the wallpaper, the iPad (presumably processing the wallpaper for parallaxing) would take up to 7 seconds, and of course the button you had pressed to set it gave NO feedback. so you just had to sit there and trust that the iPad was doing something. except sometimes the touch hadn't registered. and you were just sitting there. tellingly, in an update, apple added a message and spinning wheel.
feedback is useful and important, and iOS7 overall still gives a general feeling of disconnect and disorientation where previous versions had a sense of immediacy. its not a matter of aesthetics, you can like the new "look", but nobody's doing anyone a favour playing the "if it looks nice thats all that matters" card, because eventually you'll get bored again, and then you'll have a boring looking AND less functional experience.