Dave!
You are absolutely right, RW is not headed for gearheads like me.
But that doesn't stop me from dreaming

So here we go!
There are several things in the "mixing" process part of RW that could be better. RW is brilliantly designed for that first creative/spontaneous phase of recording with its riff/loop based approach. The problems starts when you have large collabs with 20-30 riffs with 6-10 layers in each. What happens is that you loose structure which you need if you want to do a decent mix. Several things could be better:
1. Moving layers within a riff so you get cosistent layer structures between riffs.
2. Copying layers between riffs (honestly, this request almost comes naturally when using RW for 5 minutes)
3. I wish RW could remember the placement/colours of the riffs between sessions. I usually like to group verses, choruses, intros, breaks and endings into groups of riffs within a color. If you organize them this way and then log out and then log into Rifflink again your structure is lost.
4. Administrator rights for the creator of a rifflink collab (which usually is the one mixing and riffcasting the collab) which means the admin can change or delete any riff but also protct(freeze) a riff or a layer.
5. Could it be possible to get a numerical feedback when turning a knob in RW? Just a number that tells which value you just dialed in on that knob.
6. Layered export from RW to WAV. If you have a song which you wish to mix in an external mixing program like Reaper or Audacity you need to manually export the layers of a song separately which is a tedious work.
An interesting feature would be an export option which makes RW export each layer by name (including drums and songlayers) to separate WAV files. Let me give you an example: you have an song with four riffs. Each riff consists of three layers named BASS, RYTHM and LEAD named consistently over all riffs. In the songlayer you have two Layers, VOX and CHOIRS. The song has an ID, for an example "MATTSORUM-BASIC". Now if you wish to export it "by layer" RW would create the following WAV-files (of equal length):
bass.wav
rythm.Wav
lead.wav
vox.wav
choir.wav
mattsorum-basic.wav
and it would be a breeze to import them into another more advanced mixing application. Now this was a fairly simple example which still would be perfectly manageable to export by hand from RW, but when you wish to mix a collab with 20 riffs and 8-10 layers in each it gets kind of complicated. For this to work properly you need to be quite disciplined when naming you layers.
Finally I have a rant regarding almost all VST/effects GUIs on the market today. Why do they have to look like some 70s/80s hardware? It's awfull.