Yep... silly and pointless.

Which is why such a thing might be wildly popular.

Look at PCs and desktop backgrounds, sound & appearance
schemes, application skins, etc. They are created,
passed around, used by many. Newbies in particular
go overboard when they find they can customize their PCs
with this stuff, much to the annoyance of sophisticated
users (especially with sounds).

Hell, look at ringtones -- people spend *millions* of
dollars on them.

If the iPhone allows such a thing (I don't know), there
probably already is a mod that emits manual typewriter
sounds when you tap on the screen keyboard, dings when
you hit a pre-set right margin, and makes the r-r-rip
carriage-return noise when you press enter.