How many cards do we need?

Now we have the new Geforce 8 series, we have the Physix card, not to mention the sound card and the always present network card.
Yet, do we actually need them? Can't the computer industry sell universal Hardware? (aka the good motherboard with good on-board chips.)
The answer is more difficult then it would seem at first, for one we do have the simple problem that the newest hardware, is usually not the best that can be supplied but rather that what the market can absorb the fastest. For example, the Physix card is something fairly unnecessary until games employ better physics engines. Now those cards are produced in small numbers and are over priced, yet they are still being bought. The newest Graphic cards are usually not needed unless there is a release of new Technology for example HDCP, further there is another issue that often loses importance which is that it will take sometime for new games to be released that actually can use this new computing power. Yet, it is odd that the home-user is not even offered access to the computing power that is made available to the developing companies. It sometimes also seems that the companies try to get the greatest profit for the smallest amount of work (ok I admit that that is not very surprising).
Yet, sometimes it's just odd that developers have full access to technology while the end-user is left alone, or rather is left to buy an older product so that when the new technology is implemented in a game that the end-user has to be or at least should buy a new card. It is an interesting pattern that a new card is usually released a 6 month to year before the the technology is actually used. Considering that a well developed game takes at least two years most often more.