The problem is people build a little widget that would happily fit in a box from Hammond, but they would rather have it customised at great expense and it eats into their profit. CNC is pretty time inefficient and expensive when you get to very large volumes.
The major advantage of CNC though is that if you mess up the first time, you haven't ruined an entire batch. You just send the new model to the company. With molding or die casting, fuckups can easily cost tens of thousands.
If your margin can absorb the cost of CNC - and for photography it's probably a marketing feature - go for it. Plenty of companies sell CNC machined housing simply because they can say it's CNC'd and people go "ooooh".
I'm mostly familiar with plastic molds, but for durable/production ready molds, you're normally starting off at like 20k per mold. You can usually bring your part to manufacturers (both CNC and casting shops) and ask for some quotes.
The major advantage of CNC though is that if you mess up the first time, you haven't ruined an entire batch. You just send the new model to the company. With molding or die casting, fuckups can easily cost tens of thousands.
If your margin can absorb the cost of CNC - and for photography it's probably a marketing feature - go for it. Plenty of companies sell CNC machined housing simply because they can say it's CNC'd and people go "ooooh".