It's cheap. You can end up
with many of the features exclusive to high-end guitars without paying
those kinds of prices. If you aren't looking for a "pretty" guitar
and instead want one that is highly functional, you can upgrade any decent
guitar on the market for a lot less money than you would have to pay to
get the same features anywhere else. Honestly, there is absolutely
no way you should ever play more than $500 dollars for a Strat unless it
was on the cover of a Clapton album. For that matter, Clapton's signature
model costs ~$1200. The electronics cost $250. I rest my case.
It's easy. There are probably
three ways in which a guitar can be modified: its looks (aesthetics), its
playability, and its sound (primarily due to its electronics). Of
the three areas, electronic modifications are probably the easiest to accomplish
and the easiest to reverse if you are not satisfied. Further, you
can switch between modifications so that you have the best of all possible
worlds. It would be nice if you could do that with your paint job
as well, wouldn't it?
The tone. There are hundreds
of effects on the market today which are growing in sophistication at a
ever-diminishing price. However, electronic modification at the level
of your guitar allows you to work on your tone before it goes anywhere
else. Effects process a signal. If you don't have anything
worth modifying, it won't matter how much you work on that patch, it just
is not going to sound as good as it might if you made a little effort on
the guitar itself.