The TEW-639GR costs about $90 while each TEW-638APB will set you back around $60. This means that for as little as $150 you can connect quite a large area without the need to pay a contractor to run hardwired lines to each office or room where network connectivity is needed; also considering that to extend coverage further you will only have to shell out another $60 instead of over $200 to add another cable and wall jack.
Granted, this is only if you have to hire a contractor. But still, even if you run the lines yourself, the cost would generally be more than $150 or even $200. This makes WDS the better (and more logical) choice for setting up a quick network over a large area. As there are bandwidth limitations with WDS, there will be times when a wired network will still be the better choice, but it will cost you significantly more.
On the other hand, for the home the WDS system seems to fall short of the mark and while less expensive, it would be a better value to purchase a more expensive (and higher quality) wireless router for gaming and HD video streaming.