Not so pointless because you will be able to use internet also in this case
If you connect PC->PS3 with cable, you will loose internet connection to PS3(if you don't share internet on PC) but with switch you will be able use internet also in case of PC will be OFF.
But I suppose your router is not faulty but your WIFI connection is poor, maybe noisy environment....try to use another channel on router to stabilize connection and avoid dropouts.
Also I suppose that you can connect PC->PS3 directly via WIFI in AD-HOC mode (sometihing like client-client, not AP-client). Don't know if PS3 supports it...