Why was BTS removed 
Select 1, 2 or 3
1. Bittrex don't like decentralized exchanges
2. Bittrex has added ADA some days ago. That shitcoin from Charles Hoskinson. If I remember right he was involved in Bitshares as well and there was some bad blood with him and Dan Larimer before he left the project.
3. Its still profitable to short on poloniex
For 1 they would delist Waves as well, and maybe some others ?
edit:
found this https://busy.org/bitshares/@tech-trends/bitshares-is-delisting-on-bittrex-or-13-oct-2017