Practically all my computing devices have been multitasking - Amiga, Psion Series 3x, Series 5x, Zaurus C3100, various Symbian phones etc. I would expect multitasking to "just work". The Psion devices were the only devices which simply worked, mainly because they had sufficient RAM to run the applications expected of them and because the OS is extremely resilient (virtually crashproof). The Zaurus had enough RAM if you wanted to limit yourself to the default factory OS/applications. But when you start to run things like Pocket Workstation (ie chroot Debian) or alternative distros then RAM is certainly a limiting factor. Symbian devices are plagued by the lack of RAM crippling their multitasking potential, eg the E70 you mostly can't run more than 1 major app at a time.

Think of it like Windows is overrated and yet can't be ignored