The price of NXT is going down because it is widely used for assets on the NXT asset exchange. Many asset issuers turn there raised NXT into Bitcoin because they need to pay developers which usually only accept Bitcoin. Throwing the raised NXT onto the markets creates an ongoing sell preasure.
Thats similar like the discussed thesis that the Bitcoin price must decline the more shops / sellers accept it. Shops accepting Bitcoin usually exchange them immediately into fiat money ( like Bitpay for shops standardly does ). This creates a bigger sell preasure and decreases the price.
Exactly if a lot of positive projects pay good dividends to shareholders, then BTC has to be transformed in Nxt and sold on Poloniex. Depressing the price but not reflecting the real value of Nxt as a community.