We are killing the GL1 "vanilla" renderer on our 25th alpha release, which will be this March. This is because of the following reasons:
1.) The vanilla renderer is irritating to maintain and displays things very poorly.
2.) Very few people use it, and the number will only drop over the years as people get newer hardware.
3.) We want to add features to GL3 without having to spend time upgrading two renderers simultaneously.
For the 25th release, we want to add texture compression. This will drastically reduce the file size of image assets. While we have it almost working with GL3 and it will likely be in the 25th release, we do not feel that the vanilla renderer is worth adding it to, and we do not want to distribute two separate asset packs.
However, we will be adding a switch that will allow you to quickly disable all of the GL3 effects (including dynamic lighting and normal mapping), which combined with texture compression should give you comparatively similar performance to the old renderer. That way, if your hardware is weak, you should still be able to play.