We didn't add ship design and multiple playable races because we wanted to make the game more like MOO2. We added them because they're great features. Gal Civ for OS/2 had Shipyards, which allowed you to design your own ships. We would have liked to do them in GalCiv for Windows, but we just didn't have the time to do it right, and it would have required a lot more art, which would have also increased the amount of RAM it used up. It would have been kludgy, limited, and it probably wouldn't have looked that great.
The 3D engine for GalCiv 2 has made a lot of things possible that just weren't practical, if not impossible, with the 2D engine. We've also been able to reuse a lot of the code from GalCiv 1, so we're not starting completely from scratch like we were with GalCiv 1. Well, we had interface code that was used in The Corporate Machine, but that changed a lot for Gal Civ; we pushed it past its limits and then had to fix the bugs that started cropping up. There were a couple of bugs involving unsigned short integers. 
There was also mention that MOO2's AI sucked and that only multiplayer made it fun. Multiplayer is something that a percentage of people have asked for a lot for the GalCiv series. However, one of our strongest points has always been AI, and AI always suffers when multiplayer is included.
It's true that lately we're a little sensitive about people coming on here and asking for MOO2 features. However, some of the people posting threads asking for MOO2 features have been extremely aggressive and demanding. It's frustrating, and discouraging. People keep saying things like GalCiv is the true successor to MOO2, and that doesn't help. Gal Civ is its own game. It's not a successor to MOO2. We're not anti-MOO2. We're just sick of seeing the attitude that GalCiv 2 will never measure up to MOO2 if we don't make it a clone of MOO2 with new graphics. There was one post in particular where a user very generously said that it's great that we've added our own features, but we really HAD TO HAVE all the existing features in MOO2, because MOO2 was the pinnacle of turn based space strategy games. It's that kind of post that makes us grind our teeth and start ranting.