That can happen with BSD software, too. Thr LGPL only gets more restrictive if the author releases a new version of their library that only permits the new LGPL version. Any project can change its licensing at any time, but with most open source licenses you retain your rights under the old license.
Yes, it can happen with BSD and MIT. But at least you can start a fork from there, if you really have to. Forking LGPL stays LGPL, with the limitations & all.
On the other hand I try to avoid GPL/LGPL for components.
Here is a scenario:
1. Invest in developing your app based on CppCMS
2. It takes off, great - buy commercial license.
3. The next version of LGPL gets more restrictive, you're stuck with commercial license.
4. Artyom gets hired by Google/Apple, no time for CppCMS anymore; only the LGPL fork gets fixes from now on.
5. Throw away your investment (time and money), start learning something else - how cool is that?