I’m thinking of getting this pack and your review is super helpful, thank you. On storage, have you tried the small DSLR core unit? I think it would suit the side access better because its opening is only the size of the camera so less wasted space. If you only use one or two, that would free up more space in the back for clothes etc. That’s what I’m tempted to do but I only have a one camera one lens set up so I don’t need much space and prefer to have room for layers, food etc when hiking.
I have looked at other cubes to put in the bag, but they were not in supply when I checked a few months ago, maybe they are in stock now. I don't think any other cube would work with side access because the flaps of the cube and the flaps on the pack must match to make that work. I would like to try a smaller cube to reduce the amount of camera gear storage and increase "daily" carry storage.
I think it may be a design challenge. If you really need a HUGE side access look at the Compagnon element backpack, you can drive a truck through the side access. I have a review on it
Every single one of your gripes are the same ones that I have. That front pocket is pretty much useless, too deep and too flat to be taken seriously. The top compartment is too small (i bought the 20 liter). The side access is only good for a small mirrorless, I tried it with a Canon 80D and I couldn't get it out. The rain cover storage is in the worst possible place, if it is already raining you'll have to expose your gear to the rain just to get it out and storing it out of the camera area it then eats up some of the precious storage space that is needed for your bits and pieces. The bag is comfortable and it'll carry your gear but in general I consider it a fail.
True, I will probably never invent my own backpack, but I think videos pointing out certain flaws helps people in their buying decisions and helps companies improve on future design. I think it's a great backpack overall.