There are many wonderful characters that don't have their own individual keys on your keyboard. Heck, there are a lot of characters that require at least one meta key to be pressed in combination with another key, and single quote marks are accessible in exactly that way on my keyboard too (Mac, YMMV).
And, yes, autocorrect can be a PITA, especially when it's not actually getting things correct, but that's a different, albeit related, issue. We should really refer to quote marks, or apostrophe (which are often rendered as curly, and are the characters that autocorrect switches to), and the prime symbol (which is the unadulterated character that you get with the non-meta-pressed key on your keyboard), rather than using the term 'smart quotes'.
Not to detract from the substance of your post, but the unshifted keyboard key pretty much universally generates an ASCII apostrophe (U+0027, '), not a prime (U+2032, ′, as used for feet and minutes, and while I'm babbling, the addition of a second prime for seconds is not a coincidence).
~~~~ wavy lines starting flashback ~~~~
ASCII 1967, in conjunction with its European counterpart ECMA-6, permitted the visual appearance of some characters, including the apostrophe, to be modified so that they could be used as accents when overstruck¹:
' " , ^ ` ~
ˊ ¨ ¸ ˆ ˋ ˉ (using the modern Unicode spacing modifiers)
Later versions of ECMA-6 suggested that the accent interpretation be used only when the character was actually overstruck:
In the 7-bit character set, some printing symbol may be
designed to permit their use for the composition of ac-
cented letters when necessary for general interchange of
information. A sequence of three characters, comprising
a letter, BACKSPACE and one of these symbols, is needed
for this composition; the symbol is then regarded as a dia-
critical sign. It should be noted that these symbols take
on their diacritical significance only when they precede or
follow the character BACKSPACE; for example, the symbol
corresponding to the code combination 2/7 normally has the
significance of APOSTROPHE, but becomes the diacritical
sign ACUTE ACCENT when preceded or followed by the character
BACKSPACE.²
Although this was fine for the printing teletypes in use when ASCII was first designed, early video terminals were too dumb to handle overstrikes, so it never caught on.
They don't have a dedicated key, I suppose, (but then again, you have to hit <shift> to get parens…) but smart quotes are <option>+{ and <option>+<shift>+{ on OS X, and configured to be <compose>, <, " and <compose>, >, " on my Linux machine.
Smart quote are a bit of a pain, but they do look nice. Really I prefer em dash, en dash, ellipses; I regret that OS doesn't have a keyboard entry for bullet. (Then, Linux doesn't either, other than entering in the code point directly with Ctrl+Shift+U or whatever it is.)
I created a custom layout using Ukelele that makes typing smart quotes easier. With it, opening ‘ and closing ’ single smart quotes are <option>+[ and <option>+] instead of <option>+{ and <option>+<shift>+{, and double smart quotes “ ” are similarly more intuitive to type. I use it all the time. You can try it out yourself by downloading it from http://a.pomf.se/bipwcr.zip and moving the two files into “~/Library/Keyboard Layouts/”.
Also nobody magically switches my parentheses around out from under me.