There was a very important difference between these Slivers and those from the past. Unlike older Sliver cards, which affected all Sliver cards on the battlefield (possibly including even your opponent’s), these new cards affect only your Sliver cards. This means that in Sliver mirrors, if you can get the more powerful effects on the board before your opponent can, you likely have the game won. Having double striking Slivers is certainly one way to do that.
Would Bonescythe Sliver be a part of that Sliver puzzle? It was certainly possible. Having a casting cost of 3W seemed fair, especially with Manaweft Sliver from the same set giving all of your Slivers the ability to produce any color of mana. Double strike is quite relevant, as well. With how quickly Slivers can mass an attack, this could help you stage a finishing blow.
When I first took a look at this card in July of 2013, I thought that people would find a way to stick at least one copy of this card in a Sliver deck. It seemed clear to me that White wasn’t going to be a big color for Slivers, although Sentinel Sliver and Hive Stirrings were definitely playable cards. So there seemed to be room for this card to work out. Double Strike seemed too good to ignore.
Unfortunately, outside of casual Sliver decks and Commander players running the several very good Sliver Legendary Creatures, Bonescythe Sliver never saw much play. Even when the Magic 2015 Slivers made the archetype even better, Bonescythe was basically forgotten. It just didn't seem worth the deck slot for a deck that could win even without the double strike.
That being said, Bonescythe Sliver is far from worthless, still being worth over $1 even without competitive play. The promo version of Bonescythe Sliver is worth even more. The value of this card is due to the fact that Slivers are a very popular tribe in Kitchen Table Magic. While it proved to not be an optimal play in competitive 60-card Magic, Bonescythe Sliver has become a staple in Sliver Commander decks everywhere. It's also often played as a four-of at the kitchen table, so this card definitely still has some value.