I can get the arms off my LEGO minifigs, however, will doing so repeatedly wear them out?
No, they are not meant to come off (and neither are their hands) and I imagine that doing so repeatedly will cause them to become loose, as is the case with hands.
I have noticed that the hands come off a lot easier nowadays compared to 1970s/1980s vintage Lego, but I'm rarely sadistic enough to rip their arms off :)
I did it regularly as a kid and, while it takes some effort, it had to be done a considerable amount of times for any damage to appear.
Removing arms allows for more variety in your minifigs, but also to use these elements separately for other purposes (never underestimate the usefullness of a single hand, or the architectural value of a torso).
Also, note that other arms have been produced (mechanical arm in the Agents theme, rock arms in Power Miners), so you can have interesting minifigs by using these. Same for boxing gloves recently released in the collectible minifigs serie.
One last thing - some minifigs are produced in China (for magnets, for example, or minifig collections) and there are some concerns about their quality, so you may want to be careful with these. Note that while the fact that they are produced in China (you can recognize them at the rectangle engraved in the arms) is a certainty, the fact that the quality is less good is subject for debate.
From my experience: Normally No! But you can yank them out softly. If you do it to often they'll become loose.
The only arms you can legally take off are found on Mos Eisley cantina aliens. Use the blue light saber to take them off cleanly.
By the same logic, you can only swap hands on certain Luke Skywalker minifigs. Or pirates. This is also true now for certain Anakin Skywalker minifigs.
Also, I have received several minifigures from various boxes that had no hands mounted to their arms from the factory, which indicate it is a "legal operation".
I don't think they aren't ment to be ripped off often, but if doing so gently, they shouldn't break.
They are not designed to be removed and doing so can make it hard to replace.
It is not a very good idea to remove Lego arms except on the minifigures listed above.
I've found that when a hand is pulled out it often (but not always) creates a crack in the arm, so that when the hand (or another different-colored one) is replaced it'll be a bit loose. It could certainly depend on the age of the minifig tho'.