As far as I know the game was delayed by a great deal because of two features that are missing.

One of them being Microsoft DirectPlay. This was Microsoft's online gaming service in the late nineties. In the end online play was completely redone because apparently it was unworkable. This is most likely also why the (originally announced) online co-op and race modes are missing. In the end it is good they redid it because I think DirectPlay has been discontinued for a while.

The other one is the GRADE system. Which was supposed to make the game work on both Windows and DOS. As far as I know they never got this one to work. You can still find traces of it in the source code though.

In your initial post you are looking too much at the graphics, they aren't where the real shortcomings of the game are. A lot of what was announced in the years/months prior to the release is missing. They tried to do too much, and in the end they never were able to fulfil their promises. If they had released the game a year earlier, like they planned, it would have been an instant classic.