*DISCLAIMER: you digitally signed a legal agreement releasing ESO of any consequential damage to your property as a result of using their products*

That said, if you have the kind of ESO crashes that are instantly resetting/rebooting your PC, then your OS and any running applications/services will eventually sustain damage, not to mention you will lose an unsaved work. It might not happen the 1st time your PC crashes, but eventually bad luck timing will occur and a write cycle will get interrupted at precisely the wrong time, and some files can become corrupted. The more often your PC crashes, the more concerned you should be about it. Sometimes Windows can fix system file problems when you scan for errors, but most applications will have to be re-installed if they start to show signs of corruption. Signs include things like the application locking up, menus that don't work or functions that are no longer accessible. If you are experiencing a lot of hard reset crashes, then you should consider running the ESO repair option in the launcher screen frequently (I'm assuming this should repair/replace any corrupted/damaged game files).

Fortunately you can control some of the processes on your PC, and you can use these precautions to minimize damage/corruption:

1) Close all unnecessary applications before starting the game (including browser sessions, music players, etc)
2) Stop any unnecessary services that you are aware of
3) Disable all "active" scanning from anti-virus and anti-malware programs
4) Temporarily disable automatic Windows update

As a more extreme measure, you could also boot from a clean startup just prior to playing the game. Type msconfig into the Windows Start/Run box, select Diagnostic Startup, then reboot your PC at the prompt. After the game, reselect normal startup(or whatever you prefer), and reboot your PC to resume non-gaming PC activities.




Unfortunately you cant prevent all damage. Here's a quote that gives you an idea of what's happening when your PC is abruptly shut down. (note: a pc crash is equivalent to unplugging the power cord)

Let's say that a program is updating something on disk – it doesn't have to be something you're doing, it could be some other program like your anti-malware tools, the system indexing tools, or something else that's running on your machine. If you suddenly remove the power in the middle of that operation, then any of the following may happen:

•Nothing. You got lucky and the writing actually completed, because it's so darned quick. This is probably the most common case, but it leads to a false sense of safety.

•The file that was being written is incomplete. Depending on the program writing the file, this can be completely benign or show up as a major problem the next time that programs try to access that file.

•The file system directory entry that locates that file on disk could be incorrectly or partially updated if that's what the computer was writing when you pulled the plug. This can be benign, but in the extreme case, it can actually render the file system corrupt and you can lose not only the file that was being written, but large numbers of other files on the disk. This is bad; very bad.

•The disk drive could be interrupted in the middle of writing a sector of information to the hard disk media. That could result in CRC errors for that sector and nearby information in other files. This may require a CHKDSK /R to repair or in the worst case, it could even require more advanced disk recovery and maintenance. Fortunately, with modern drives, this is typically rare.

Hopefully, you get the idea: just pulling the plug is a bad idea and should be used only as a last resort and immediately prior to resolving any underlying problem that required it be used.

Sources:
http://ask-leo.com/can_i_just_unplug_my_computer_to_shut_it_down.html
http://www.dummies.com/how-to/content/what-happens-when-you-shut-down-a-pc.html
http://forums.cnet.com/7726-7591_102-5200646.html
http://www.pcworld.com/article/191107/hasslefreepc.html