The sound waves do indeed, at least to some extent bounce back from the floor, go through the driver cone and back into the enclosure and, while that's not necessarily the greatest strategy sound-wise, it will not really mess things up all that noticeably if there is sufficient airflow at volume. Were all the walls of the enclosure to extend down to the floor cutting off the woofer to the outside air then at volume such a sub would sound absolutely terrible and probably blow itself up. But sound waves at low frequencies tend to be more omni-directional, so having them pointed directly at the ear is not thought of as critical when crossed over low enough in frequency.
While not treating the woofers like higher range drivers and pointing them at the listener is not as critical, doing so, for a number of reasons technically, is still a good idea and all else being equal the direct setup will sound better in terms of things like phase response, frequency response...even dynamics.
This was likely a design trend that was originally employed to offer better integration into a decor by giving it a more "furniture" look, sometimes in conjunction with a reduced size enclosure for a smaller footprint. Otherwise in general there is nothing particularly good performance-wise about that kind of approach, but they are not really egregiously bad sounding or anything.
While not treating the woofers like higher range drivers and pointing them at the listener is not as critical, doing so, for a number of reasons technically, is still a good idea and all else being equal the direct setup will sound better in terms of things like phase response, frequency response...even dynamics.
This was likely a design trend that was originally employed to offer better integration into a decor by giving it a more "furniture" look, sometimes in conjunction with a reduced size enclosure for a smaller footprint. Otherwise in general there is nothing particularly good performance-wise about that kind of approach, but they are not really egregiously bad sounding or anything.