As smartphones and in particular have matured, so the size of operating systems and applications have grown. There are several reasons for this, but one is feature (or code) bloat, whereby the 2015 versions of Android contain many more features than Android back in 2009. By way of an example, Sony Xperia M4 Aqua comes with a box quoted 8 GB or 16 GB, but after installing all stock application updates, the amount of space available to customers is either 1.3 GB or 9.3 GB, respectively. The operating system and stock applications by themselves occupy around 5 GB of that 8 GB or 16 GB of internal storage, but of course there have been many application updates since Sony created the stock ROM of the device.
The issue is not just a Sony one. In 2013, Samsung was cited as having a particularly bloated ROM installation and of having the least amount of internal storage space available to customers. So, should customers buying a device with a claim of 8 GB (or 16 GB, or more) internal storage be upset if the amount of space that is actually available is considerably less? For owners of the 8 GB Sony Xperia M4 Aqua, the issue is likely to get worse because assuming applications continue to grow in size, by this time next year customers may be seeing less than 1 GB of free space after updating the stock applications. That manufacturers provide a MicroSD card slot is helpful but not all applications can elegantly run from the memory card, or even be installed to the card.
One way that the issue can be resolved is to allow customers to uninstall stock applications without resorting to needing to root the device. This, according to some manufacturers (and carriers, because not all bundled applications are on a device because of the manufacturer) would not be in the interests of the customer experience. Except, how many customers genuinely look forward to having a carrier application present on their device that cannot be removed? And how many are frustrated when they do not have enough application storage memory to update an existing application but it will not run because it is not the latest version? Or after setting up a device, then must wait for several hundred megabytes of application updates to arrive and be installed. And customers buying a device that says it has 8 GB of internal storage should reasonably expect to have little more than 1.25 GB after updating the stock applications on the device as part of the normal device set up.