And here are some the simple reasons why.
An animation program such as Blender should always remain self-contained. Leaving the door open to 3 rd party development is fine but depending on it is just a bad idea. An artist should open up a 3D program and be able to go from concept to rendering the final product and only have to resort to the same consistent documentation, work flow, and so on. 3rd party products should be the choice of the artist not the requirement. And dropping development on something as vital as rendering is simply short-sighted and goes against the spirit of Blender - and other apps for that matter - in providing a one stop solution for the completion of a product.
Decisions to use other composting programs is a choice, for instance, not a requirement. One has one in Blender. If we are to stop development on that and the sequencer as well? Sure many artists use a whole tool box of various programs. That is fine. It just should not be that an artist is forced to do so because the internal render engine has not seen any development for some time. Sure the current engine has been lagging. The new one is much better and needs improvement. That should continue. Don’t set up intentionally the same problem Blender has had as a result of an outdated rendering package all these years to date.
I personally do not like using Yafaray and the idea of an external renderer, as far as what I have seen in other packages as well has always seemed to present problems. That is my personal opinion.
Also think it is a bad idea to suggest that developers should make thier priority another software’s functionality. And literally dreaming to suggest that stopping dev in one area would give enough time to solve the complex issues of using an external engine. It is also just backwards as far as a priority is concerned. The priority should always remain dedicated to Blender. And also if the effort to solve the problems of an external engine should fail? Or not be up to the expected level? Then what?
Blender foundation is formed on the concept of forwarding the Blender platform not other 3rd party software. It would borderline on criminality to abandon the development of such a vital part of Blender in favor of supporting another program. This is for many reasons. And there is no guarantee that the Yafaray or other 3P development will continue in the far future. Should development of those softwares come to a halt it would leave Blender without a vital appendage. Time and effort lost to put a viable rendering capability back into Blender in the future would be exponential at that point. There would be too much time and effort to make up. And it could cripple Blender indefinitely should that come to pass.
So you say, “well that could never happen.”
But I say. Why even open the door for that? It is a real possibility. And sure Blender development could stop as well. But fine. Let Blender live or die on it’s own merits or lack of, and don’t waste vital time and effort catering to 3P software.
It would also be a huge disservice to the Blender community to assume that everyone would want to go with a 3D solution for rendering.
Look around at the gallery. How many use the internal render? Why?
Personal preference, lack of aptitude or desire for using a plugin. The list could go on.
I Support Blender for it’s spirit which is to offer a one-stop-shop for making animation without an undue dependence on other software to complete the task for which Blender and other programs like it have been developed to perform.