well more rack wart than underpowered I guess - the uZeus - it takes up rack space... & it's not a great power supply, can be noisy and is tbh a bit underpowered... but sufficient for the rack you have pictured...
I think mixers are incredibly useful - especially matrix mixers - for creating interesting modulation...
I don't think you really benefit from a clock divider that much in this rack - not a lot to trigger & marbles can do clock division...
possibly don't need the output module - I'd get attenuators instead... unless you need the headphone output - and then I'd get the ALM hpo as it's only 2hp - odd hp modules are a pita
sequential switches are useful
as I said above expression pedal and to some extent on/off pedal interfaces are really useful - especially if you are going to play guitar or bass into your modular
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities