While I hate the issue, too, there might be disadvantages for the buyer, too. For example if the auction gets extended for 3 hours with each bid, it might mean that you have to sit around forever monitoring the auction if you really want the item.
A better fix might be to allow sniping (automatic bidding in the last second).
The reason for last second bidding is to avoid the pitfalls of human psychology, I think. If you start earlier and outbid other people, they might get into a bidding frenzy and prices will be driven higher than what makes sense.
I suppose ebay outlaws sniping because they actually want that effect: the higher the bid, the more money ebay gets. Personally I would prefer to decide on one price and stick to it, so sniping would be perfect for me.
All in all I suspect that ebay tested the "prolong the auction" feature and found that not prolonging it somehow works better - or at least it used to work better.