i do not second all your conclusions.
why should we change something that brings more disadvantages than benefit?
in the most usual case, you have only one viewer and its including timeline on the screen. if you would put the timeline into an extra panel it will take more space, not less(!), because this extra panel needs additional decorations...
and if you have more viewers on the screen and you want to hide the controls on them, it's very easy to do. all the necessary functionality already exits -- just use the context menu.
so, why should we break this well working behavior?
no, that's not the case now!
the 'L' key is usually bound to something else outside of the viewer!
this kind of changing key code semantics in dependency of the actual focus does not look very nice, but users of compositing solutions and other similar complex software with lots of shortcuts get used to it.
but what i definitely do not like, is the binding of "O" for 'toggle overlay' in the viewer.
it's not, because "Q" (like in nuke) would look so much nicer, but "I" and "O" are very common options to set the 'in' and 'Out'-point at the actual position on many other viewers of video processing applications. that's so common, that nobody does expect something else.
but i general would not overestimate the need of more global control because:
a.) if several viewers are ganged by the 'lock' icon, it does not matter which one of them has the focus, your key press will lead to the same result.
and for contrary case:
b.) they are not connected, than it is necessary to control them individually by their own keys and control elements.
but that's all quite close to the present behavior...