Yes, and no.
Yes, in that sniping tools do help you to avoid the temptation to engage in a last-minute bidding war, as it allows you to set your maximum bid and then forget about it.
No, in that most people don't use sniping tools for the above reason. Instead, they use sniping tools such as Gixen so that a) they don't have to stay up until the middle of the night, and b) so that they don't have irrational eBay users place bid after bid after bid in an attempt to compete with the max bid that was placed by our original bidder, thus driving up the price.
First, I'm not arguing against Gixen which I understand is more than just a sniping tool.
As for the rest of this, I think I have addressed this at least twice in what I've already written. It should not affect your behaviour if others aren't putting their max bids in, because you can assume that at some point they will put those bids in, either through the normal bidding process or through sniping.
You will end up paying the same amount in most auctions, unless the other person is irrationally not posting their max bid AND they aren't sniping. This is increasingly unlikely.
Well, I think that sniping is becoming more common, and that is a good thing, as it helps to reduce irrationality.
I think that you underestimate the irrationality that is present in a market like eBay. I know (like fxh) that anecdotes are not reliable, but I have seen example after example of people placing bid after bid after bid, steadily driving up the price, in an attempt to find out someone else's max bid. I think that there are a lot of people out there who really don't understand how eBay works and so who do not put in their max bids - they put in a smaller bid and then, if need be, will put in a larger bid in an attempt to once again become the top bidder. Therefore, if you don't put in a max bid early in the auction, they will not place bids against your max bid amount and they will not drive up the price. Are they acting irrationally? Yes, they are. Are they going to stop? Probably not. Therefore, using a sniping program like Gixen helps to avoid driving up the bids and allows you to potentially win the auction and thus purchase the item for a lower price.