Here's the thing. To my understanding, Phase two was to have a curtain (?) wall similar to CIBC Square. Phase 3 was supposed to have a rooftop glass enclosed restaurant of sorts. Both of these are gone from the current plans...
...now I believe it was suggested here when those changes where posted that the newer design would be more expensive to build. Personally, I now think that was a load of spin and poppycock. As I can't see how the current design would be so, outside of using more materials because they just added more floors. Hence and therefore, it got value engineered, IMO.