For me it's an anti-sales tactic unless it's a product I already love. Why would I buy something I might fall in love with knowing that it will no longer be available? I'd just rather not know.
Now, sometimes it's becasue they're going to come out with a new and improved version, but for cosmetics that may not really be the case. There was an SSC product (Creamarum) I rather liked, but when they came out with the improved version (Creamarum Evolve) I didn't like it as well and because they had "improved" it they also upped the price of it.