Why should we fund a project that has repeatedly ignore its own community? Why fund a project that has numerous Google SoC projects not merged in? That is wasting donated time and money.
In a way I agree with you, but on the other hand I use GIMP all the time and think it's fantastic, so I might be willing to donate. Also, in principle GEGL has much more wide utility than just as a filter stack for GIMP -- it's a pretty general-purpose image processing library.
Maybe funding will allow them to direct attention more towards desired features - whilst generally I gather OS contributors prefer to work on features that interest them rather than necessarily the ones the community en masse prefer.
Donations might also free developers time to enable GSoC projects to be merged in, if indeed this is why it hasn't happened yet.
Why not focus on building an UI for Gimp that doesn't feel like trying to juggle rabid ferrets with cooking gloves on? I'm sure that somewhere behind that slightly autistic facade there is a lovely graphics program trying to burst forth.
