I don't think it was taken down because of abuse, the inventory tool is still active. The bid tool is no longer relevant because YSM is no longer adheres to strict auction-style ranking of ads.
The quality component makes the bid tool obsolete, and showing actual bids would make it easier to deduce their quality algorithm, in turning making it easier to game the system.
The Overture bid tool was great for estimating the potential size in dollars of a keyword-market. Now that all big PPC programs have moved away from auctions, does anyone have other ideas on how to come by a decent estimate?