Premature Burial is basicly the equip spell version of Call of the Haunted, with the small differences that you need to pay 800 life points to activate it and that the monster is destroyed only if the equip spell is destroyed.
In my opinion, the only reasons good enough (in my opinion) to get it banned, was the extra search (hidden armory) an equip spell has over a continous trap and the fact that, unlike Call of the Haunted, you can activate the turn it gets added/bounced to your hand.
At one point, Monster Reborn was legal (at 1) and Premature Burial was banned. But, really? How cheated could it get if people had access to 1 (only 1) premature burial? I don't think people would go main deck a search for equip spells if they don't run any equip spell except preature burial.
Also, some old cards got errata'd so they could at last come out of the banlist, like Crush Card Virus and Ring of Destruction.
So, in my opinion, Premature Burial is not as broken as some people say it is, especially if it is only at 1