知乎回答草稿箱：long long
有意思的问题。我们先来看看long long的发展历史。
世有
long int，然后有long long int。long int常有而long long int不常有。
在C89标准中没有long long，但是给自定义的新类型留下了空间1：
There are four signed integer types, designated as
signed char,short int,int, andlong int. (The signed integer and other types may be designated in several additional ways, as described in 3.5.2)
这可能是因为C89标准制定时64位编程还没有那么流行，也可能是在当时主流32位CPU（486DX是在1989年发布的）上跑64位运算需要两个寄存器辅助，就像现在的__int128一样（猜的）。
随着应用的发展，64位操作的需求庞大起来，于是几个当时的编译器厂商都不约而同地实现了自己的64位扩展2：
They are implemented by many vendors. 3 years ago, there was an informal working group that included many vendors, (addressing 64-bit C progrmaming models for machines that also had 32-bit models), and the general consensus was that as much as we despised the syntax, it was:
a) Already in CONVEX & Amdahl, at least
b) Already in Gnu C
c) And various other hardware vendors either already had it in or were planning to.
用户开始呼吁标准委员会将long long加入下一个发布的C标准版本。有趣的是，这个讨论的发起者J. R. Mashey特意在邮件中加了一条“背景信息”2：
BACKGROUND
If 64-bit microprocessors are unfamiliar, consider reading: John R. Mashey, “64-bit Computing”, BYTE, Sept 1991, 135-142. This explained what 64-bit micros were, the hardware trends leading to this, and that there would be widespread use of them by 1995 (there is). While a little old, most of what I said there still seems OK.
可见像64位CPU这样的新事物足以把当时早已熟悉x86的人们弄得晕头转向，也难怪C89标准没有long long了。
同样，C标准委员会对主动加入一个新类型并不是很反对，他们只是不愿意先于大众做这件事2：
Somebody in this group was also on ANSI C committee, and observed that fact of long long not being in ANSI C was no reason not to agree on doing it, since standards generally codify existing practice, rather than inventing new things, when reasonably possible.
果然在C99中，long long被正式确定为一个新类型3：
There are five standard signed integer types, designated as
signed char,short int,int,long int, andlong long int. (These and other types may be designated in several additional ways, as described in 6.7.2.) There may also be implementation-defined extended signed integer types.) The standard and extended signed integer types are collectively called signed integer types.)
所以回到题主的问题上来：为什么C采用了long long int表示比long int大的整数，却使用char表示比short int小的整数？short short int不是更好吗？其实long long int才是一个特例。题主也说了，这是一个历史包袱。
long long int是随需求发展而加入的类型，为了契合各厂商已有的实践而标准化。这名字的好处，一是在于它没有向语言添加新的关键字，不会让所有历史代码一夜之间废掉，二是它非常形象：什么比long int长？long long int。
再者来说，char诞生之初就与字符（character）紧密联系1：
An object declared as type
charis large enough to store any member of the basic execution character set. If a member of the required source character set enumerated in 2.2.1 is stored in acharobject, its value is guaranteed to be positive. If other quantities are stored in acharobject, the behavior is implementation-defined: the values are treated as either signed or nonnegative integers.
char是能保证存下所有基本字符（大小写字母、0-9、29个标点符号、空格、horizontal tab、vertical tab、form feed）的最小类型，恰好和ASCII字符大小一致，为8位。这也是最初表示字符的需求决定的，你觉得char* str和你提议的short short int* str哪个更直观？
所以一句话总结：long long int作为在标准制定以后因需求而加入的类型，与char这种标准制定之时便有需求的类型没有命名上的可比性。