As for covering them in landscape, the Samsung tablets, for example, have the speakers in the upper halves of a normal landscape mode.
But I referred to this particular case, the Nexus tablet.
Front facing speakers totally beat having the speakers point out the bottom or sides. That kind of design simply makes no sense at all, except perhaps from designers who care more about form than function.
Yes, but sound on a device like this is always going to be a compromise no matter what due to it's small size. It has sound, that's about it. So your point, while it looks valid in theory doens't end up being that big of a deal in the end anyway. That's how I look at it.