Speaking in strictly free software terms... using LGPL over GPL is not about opensource/free software, it's about proprietary software. To use someone else's code, and not give back to the community. I don't know about you, but I like free software.
Trolltech believes in free software, which is why we dual license Qt and Qtopia, one of those being GPL, and not the LGPL. This way, the software and it's derivatives always remain free to everyone. But we understand not everyone wants their software to be open source, so Trolltech also releases Qt under a commercial license.
The commercial licenses pay for Trolltech to continue developing a great cross platform toolkit. So, even if you are paying for a license, you are contributing to free software.
If you are in business to make a profit, you should pay for tools you use. It costs far less to purchase a commercial license for Qt than it does to hire one developer for a year,and I really doubt that one developer could develop anything as impressive and easy to use as Qt in one year.
If you are a small business and cannot afford Qt's commercial license, and don't want to open your sources, you can look into Trolltech's Small Business Program There is also the Qtopia sdk license, which is a fraction of the cost of the desktop commercial license, and it's more fun too.
Plus, nothing is stopping you from making a little money off of GPL software, just make sure you read the license and know what you need to do.