This reminds me of the FeedZeBirds asset, which was also a profitable website and after the IPO they seemed to have stopped working on it without paying a single dividend, because other projects became more important

TL;DR S.DICE is overvalued - company should improve its management
A) FZB is nowhere near as profitable as SatoshiDICE currently is, and FZB did not promise dividends. Investing in FZB is a different strategy for very long term speculation on the price, because a service which enables anyone in the world to advertise via Twitter has serious potential. The future of FZB is likely to achieve a certain development and feature set, and then be sold for far higher to a purchasing company (how and when we seek this is a strategic decision), so owning shares in it long term is a bet on that possibility.
B) It probably looks like FZB dev has slowed because we're building some other infrastructure which FZB will be using.