The high number of watchers could be explained by the fact that many people are not willing to bid until the reserve is met. Low opening bids with no reserve cause a high number of bidders, many of whom will be set up to receive alerts when they've been outbid. It creates a competition where bidders often don't want to let go and end up bidding more than they planned to. Snipers will also be more willing to set up their automatic bid for the end of the auction if the reserve is out of the way or if there never was one.

Also..For some, the other bidders convince them of the value of the item. A reserve is only the seller's opinion on the matter. Existing bids reinforce the idea that the item is really worth that much.