[carve]

1) Your tastes will change, but your tattoos will always be there. It's like picking one shirt to wear for the rest of your life. They WILL look dated in 10 years, and people will be able to estimate when you got it based on the style.
2) Interrupts the shading and lines of your skin. Especially bad if you have great muscle tone, like you do. You can see "big", but not the lines of individual muscles. Bodies are sculpture- not canvas.
3) Can't change them based on the occasion. Bigger deal for women who might want to wear a nice dress or something...like at her wedding perhaps
4) They're traditionally more common in the lower elements of society, and are still more common to those elements today. I'd bet gang members and heoin addicts are much more likely to have tattoos than entrepreneurs and businessmen. First impressions are important. Again- this is an even bigger concern with women- a lot of guys will treat them like sluts, and they'll have a MUCH tougher time landing a good, classy kind of guy. I know a really cute, smart, adventurous girl who's in MEDICAL SCHOOL who has this issue due to her two 3/4 sleeves, and she acts kind of desperate as a result because she can't attract the kind of guys she likes. Without the tats guys would be falling all over her, myself included. With them, she attracts dirtbags who think she's easy.
5) They're going to fade, and your skin will sag as you get old. It conveys a lack of foresight and concern for the future, not to mention they're going to get ugly
6) It's not a very efficient place to have a large picture. It's hard to see, and smooth, flat surfaces convey images without distortion much better. Much of it you wouldn't even be able to see without a mirror.
7) Most of the detail blurs together when you're a few feet away, and you just wind up with blueish greyish yellowish splotchy arms. It looks sickly
8) Health: they hurt to get, can be more prone to infection and damage while healing, are more prone to sunburn and thus cancer, and take extra care in the sun to prevent fading.
9) It shows a lack of self-respect for one's own body, and consequently others might respect you less than they might otherwise. It's intentional, permanent damage to your own skin...not too far removed from cutting/decorative scaring IMO.
10) It typically isn't even that expressive. It's just a picture. If you have to explain it, you could just do the explanation without having the tattoo, making the tattoo pointless.

All that, and they're expensive if you want a decent job done. Other than that, not too much more.

Now the advantages
1) You have a picture on you that you liked when it was new
2) Maybe it's a reminder of something you won't let yourself forget. It had better be BIG, and if it's big, would you forget it anyway?
3) ?