Should I recommend sealing classes by default?

Question

In a big project I work for, I am considering recommending other programmers to always seal their classes if they haven\'t considered how their classes should be subclassed. Oft

Answer 1

I only seal classes if I am working on a reusable component that I intend to distribute, and I don't want the end user to inherit from it, or as a system architect if I know I don't want another developer on the team to inherit from it. However there is usually some reason for it.

Just because a class isn't being inherited from, I don't think it should automatically be marked sealed. Also, it annoys me to no end when I want to do something tricky in .NET, but then realize MS marks tons of their classes sealed.