Region locking is a travesty which illustrates the power large media firms hold over us. As a consumer I should be free to purchase any legal title from whomever I choose.
I understand the frustration, as I have it myself, but there are reasons for this, and a lot of it has to do with licensing (and actually works to protect independent artists and filmmakers as well as the large firms). The best example I can give is Spaced; Spaced is the Channel Four series that Simon Pegg, Edgar Wright, and Jessica Stevenson did a couple years before they started work on Shaun of the Dead (and it is amazing, if you haven't seen it). However, due to how licensing laws work in the UK vs US, the music and creative content used in the series was not cleared for international use; this means that the artists involved in making the content that makes up part of the series are not being compensated properly by the laws of countries other than Britain, so until all those clearances are worked out, Spaced will not be made available in region 1. As a fan of the series, I bought it on DVD, mostly just because I like to support the filmmakers I respect, and I will buy it again when it is released over here...
Yes, it is frustrating. But then as someone who works in music, I don't want my artists to have material that they should be earning money from being given away for free while other people are earning money from it. It's still a very grey area of the arts industry, but the end result is the more lax these restrictions become, the less money that the actual artist makes (for example, taxes that are drawn from blank media are paid out to the major labels, not to independents [in actuality, no matter how the actual tax laws are written]). This is certainly different from mp3s, as most people who download music end up buying the stuff they really like; in this case, the item has been paid for, and most consumers would assume they've done their part to support the artists involved, when really no support has actually made its way to those artists.
There are, of course, several other reasons which are more about the movie industry controlling release dates and the like, but licensing is a part of it, especially in regards to regional programming (not as much with film, as most film licensing deals include global usage ryders). In probably 5-10 years, this won't be an issue, as the dominance of tv on dvd has lead to broader scopes to licensing contracts, but for now this is a big part of the issue, and while it does protect the corporations, it also protects the artists.
All that said, there are ways around it, some of which have been mentioned here. What I suggest is buying a cheap internal (around $15-20 for a DVD-ROM only) or external once you've used up your 5 changes and using it to view or rip dvds. I personally have an office machine set to region 2 and my main set to region 1, which sorts the problem for me...