There are all types of auctions, reserve auctions are an everyday occurrence off ebay, so not sure why anyone would be fazed about those on ebay. 

It is just another seller tool that may or may not contribute to a successful sale.

I don't think it wastes anyone's time. Bidders choose to bid in this type of auction. If it is not appealing to some, then you can just stick to non-reserve auctions.

With this type of auction the bidder can bid, and know immediately if they have met the reserve or not and can move onto to bid on other items, and in a market such as vehicles this type of auction may one the factors that is attractive to a buyer.  

In this type of auction a seller might also use bidding activity as a bit of a gauge to what the market might be willing to pay, and in the car category can even lower their reserve during the listing (if a buyers bid is higher than a lowered reserve, it is automatically lowered to just beneath the reserve price).

I think a trading place that offers choice in selling format is a postive thing, as it may attract a wider range of buyers and gives a seller a little more choice in how they wish to sell their goods.