Compilation of kernel in a Linux system makes it better adjusted to the given hardware and consequently speeds up the system. Also, many Linux newcomers have heard many times that there are people compiling their Linux kernels to achieve greater efficiency. Some of them would like to do it too, but without any programming background and knowledge of Linux internals they have no chance of succeeding.

Ubuntu and all other Linux distributions tries to implement drivers at kernel level or something like that...
Why linux volunteers write driver ?
Linux should prepare only platform for device driver, not write driver code itself...

after the driver platform, any volunteer may develop driver, but DEVICE VENDORS SHOULD BE encouraged and helped to write drivers for Linux using that driver platform...

Most computers these days have thermal, voltage, etc. sensors which can report data to sensord and the system. Moreover, those computers usually have firmware built-in thresholds for such sensors: if the kernel detects one of those thresholds has been triggered, it will initiate a graceful shutdown.

I reckon that such ACPI signals mean the computer is in danger, and thus that it should power off ASAP. However, I think the kernel should try to hibernate instead of shutting down just like that, since the current behavior is quite surprising can make users lose work.

My proposal waters down to the following:
1/ An ACPI threshold is triggered and detected by the kernel
2/ The display is automatically switched to a free console VT, with the something along the lines of: "WARNING: your computer is being shut down to prevent it suffering damage. The following condition has been reported: (human readable explanation of the problem here). The system is trying to save your work to disk and will then power off"
3/ The system starts the hibernation routine, giving it 5 secs to freeze everything and actually start writing things to disk
4/ If the hibernation routine is not able to start in that time, X is killed, filesystems are unmounted as cleanly as possible and the computer powers off

An important point is 2/: the fact that the computer can tell you something is wrong with its systems instead of just powering down without explanation (and post-mortem analysis of dmesg) is very important. Moreover, getting out of X (and maybe Compiz and such) will probably relieve pressure off the GPU. Possible warning messages would be:
-Thermal: "The temperature of your CPU has exceeded 120 ºC (whatever ºF)"
-Voltage: "The +12V supply is too unstable (outside a ±10% safety range) and could damage components"
-etc