I live in a trilingual area. When you buy a computer you have to decide which layout you will be most typing in and then stick with that. For many people who need to switch a lot between languages it would be nice to be able to set and see the keyboard layout according to the language used, like one can do on mobile phones and tablets. The same goes for shared computers at home (bilingual family here), in offices or on production floors.
Personally, I use Apple's english international keyboard layout as that gives me full access to the characters needed when coding, while allowing me to generate special characters (accentuated, grave, acute, umlauts) easily enough when needed, and I can't see myself switching keyboard layouts for different tasks.
Some other possible points:
- Applications with particular needs can offer special keybindings and display them on the keyboard directly.
- Some manufacturers sell their laptops only with the "national layout" - people who want that brand have to buy a new keyboard with the desired layout and then switch their laptop's keyboards (potentially voiding the warranty).
- Logistics for the manufacturer - it is no longer necessary to have different keyboard layouts for the major languages. That depends on the cost of the keyboard, though.