It's for quick setup and helps prevent errors and cable damage.
Have you gigged much? You'd understand... You sometimes get 10 minutes to setup and sound check.
I set my case down, take off the lid, run my FASLink cable to the front of rack panel and done.
No arranging, no other cables, everything works and is securely in place.
Eric Johnson does what you're talking about and every single time I've seen him perform he has problems with his stuff on the ground.
Much less gigging these days, but when I have it was as simple as set MFC-101 on stage, plug in ethercon cable, and plug in my 2 EXP pedals with short TRS, which allows me to position the pedals in a bit more ergonomically friendly position for me as I like them angled, not parallel with the MFC.
I've built plenty of pedalboards over the years, and yes, they make sense when you've got a bunch of pedals, patch cords carrying audio (way too many bad George L's to speak of lol) and also the need for a power supply. Total sense, but if we are talking just a Foot Controller and one or two expressions pedals, with nothing carrying audio, everything powered by one Faslink cable etc, it just seems overkill for me.
Its not different than if someone said they used one hardware stomp box...Would I spend $100+ to mount that to pre-made board ? No way. But that's just me..... and my opinion. I've always considered all the premade boards very poor values. I can do basic soldering, and very basic wood and metal work, so I've always been able to build my own custom boards for fractions of what the name brand stuff costs, and with no trade-offs in sizing, not enough power ports etc.
People can all do what they want though, so thats great. Some folks will likely just have the FC sitting on stage, maybe with 1 controller. Others will have it attached to a pre-fabricated pedal board with matching case. Some may have it attached to a $10 particle board shelf from IKEA lol. Any and all will work fine.
I will say with regards to pedal boards in general though, I used to do the super near custom wiring lengths, carefully routed patch cords etc, and that is well and good. Gets lots of "likes" on threads lol, BUT, the big issue I ran into was when I changed a pedal, say from side to top mount jacks, suddenly my wiring was too short, or the power cable didn't reach and it took a lot of work to redo it, which was a big PITA.
These days I'm 1) not playing out which has its own luxuries lol, but more so, 2) not mounting any of my hardware pedals and while messy, has been really fun because I can plug things in different orders. Do I like my Klone before or after my muff style fuzz ? Where do I like my vibe pedals, before or after the fuzz ? Kind of fun being able to change stuff up, since they aren't all dual-locked down to a board in a given order. Kind of goes back to the Jimi thing, where he'd grab a given fuzz flavor of the week, and maybe he'd put it before vibe, maybe after etc. I like that mentality, though again, I'm not knocking folks who want to dial in every pedal, shorted each lead to the perfect length, tape or goop their carefully set knobs in a given position and just plug in the board and know exactly what it will do week in/out.