That makes sense. External storage is best for keeping libraries of documents, media, and the few documents that no one in their right mind would put in the hands of strangers.
Btw, Android after 4.4 it doesn't move/install apps to extsd. Of those that permit moving, their executables stay on internal memory. Only some of their data is stored on ext storage. If executables were on external storage and it was inaccessible, lots of things would be broken
Putting executables on removable storage is a really bad idea. Sneakerrnet is one of the biggest threats to system integrity. (When you are external sorage, no one knows where you've been, or if you can be trusted).
The advantages of ChromeOS are a clean working environment every time you log in, hence few ways for anything to install malware onto a device, and the overall improved security/safety of having most of your data in a reliable datacenter.
[rant]
As a former IT network engineer with roots in the pre-network days, I've seen a lot of improvements in hardware technology, but few in either software integrity or users.
Even when it works right, most software sucks. It's bloated, CPU and memory hungry for little gains in utility.
For instance, an old re-PC could connect to CompuServe and make airline reservations in the 1980s on a microcomputer with less than 64 KB of RAM and NO internal storage. That's less than1 Millionth the computing power. For all the improvements in hardware and cost, I don't see a million-fold increase in utility or the value of the output. As billions of old fewest and take pictures of events but their lives that have little value to anyone else except as timd wasting entertainment, storage has exploded while knowledge of lasting value hasn't. [/ rant]
Having experience many buggy Android apps that didnt live up to their descriptions of cravings, but required reinitializing my tablet, I'm very leery about using more than is absolutely necessary on ChromeOS. That may limit me to highly popular ones like Skype and perhaps one of the highest rated file managers.
I'm waiting to see how ChromeOS handles Android app installed. If it converts them to machine code as Chrome apps are, or puts their javascript form on the internal SD.
I hope it's the former.