Who said the computer components you're looking for are in the dash? I mean I'll be honest, I dunno about these modern vehicles, but vehicles I've worked on in the past have the main computer in weird unexpected places like under the driver's seat or in the passenger side cowell area.
I do get your point though, yes such modifications might be simple on paper, but cost quite a bit in labor to actually accomplish.
Regardless, I've done dashboards too, even drove my car around for a day with the entire dash completely missing, because I needed to drive it to the store during service that took me two days.
Hooray for dumb cars!