With the code within BI full of hacks on top of hacks and bandaids (according to those who tried to work with the code), chances are few would be willing to do the work needed to clean up the code in a way where you can safely add features without breaking others.
It’s probable that the state of BI’s codebase is a major reason why we now have the Cycles engine, the idea that cleaning up BI would be as much work as starting from scratch and getting better results.
better results in SOME areas, I’ll grant you. But since when do Blender folks
want to be building renderfarms to do their animations? Last time I had
a render that was an hour + a frame - 2002. The Render of one minute took a whole month! + tied up my main machine. Came out nice though.
BI can’t be improved because there is no one around to work on it and the one person who was working on it often, Breacht doesn’t want to work on it because he thinks the code is a mess. If he want from the stuff he did for Sintel in the render branch to this it should tell you something.
And seriously BI is the reason most Blender renders look like the belong in the 1990’s. Everytime I look at a BI render I feel like am watching something from that era; look at something like the Diablo 2 cut scenes, tranformers beast wars etc. Anything from that era will look like what most BI renders look like now
I think that the BI could be improved a lot, and easily.
For example the current raytraced AO could be transformed into a good pathtracer with a little effort.
In the last 2 years I sent some bug reports to improve the BI, but most of all where closed without investigating.
Probably there are no developers available.
GPU programming is difficult and time consuming, it seems to me very hard to add in Cycles all the features of the BI in a short time and doing it in CUDA, OpenCL and C++CPU at the same time.
I use Blender for planetarium animation production, at the end I had to write my own rendering engine, just to support that simple Fisheye camera.