A) Yup, definitely begging to be stolen, but other things in my car are as well, so what's one more thing?
B) Yes, they do cost a fortune, but if used right they can last quite some time.
C) I agree, that there is no major reason, but it does allow me to take some of the extra stress off of my regular 3-Way speakers. Plus, I like the additional bass, it does make some stuff sound a little better.
D) If used in a more responsible manner you don't really have to worry about cops/fines. If the subwoofers are kept at a decent volume you can hear (and feel) it in the car considerably well, while not disturbing anyone around you.
E) Again, if you keep the levels right, the trunk (and other parts of the car) won't rattle too much. And if it does, there are options, such as DynaMat, or, in some cases, just simply tightening some bolts or screws.
F) Nothing can make rap sound better, without some kind of drastic change in the songs themselves.
G) If I go deaf, that's my problem. But, again, keeping the levels at a decent volume, you should be fine.
If used responsibly, and set up right, you'll be fine. My system can hardly be heard outside of my car, less I have my sub-woofer level turned up considerably high, which is just excessive, annoying, bothersome, and, as you mentioned, illegal in numerous places.
All-in-all, the whole point of this post was to say I agree with what you said, but at the same time disagree. It's all about how it's used. You shouldn't have it up real loud at night when people are probably sleeping, nor should you have it up so loud that it bothers the people around you. Just enough to accent the sound that's already there from your original 4-8 speakers.
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AIM ID: BlueViper192
RiP -MaDaVentor-
The Limelite