BTC is stable until it is not... I would rather have a peg with one or more of the stable coins, whichever is considered to be the best, for those who want to keep some funds in a more stable crypto (compared to USD).
But it's important Steem-Engine has pegs for top currencies as well. Among the known coins, besides BTCP, there are also pegs for LTC (LTCP), EOS (EOSP) and BTS (BTSP).
It is good to know for the other pegged crypto.