OFBiz already has functionality to encode output in addition to the functionality that filters input. In discussions about this security aspect of the project we decided that doing both would be best, especially since there are possibilities of holes for both filtering input and encoding output.
Please consider that we want the defaults to be as secure as possible and allow ways of doing things in a less restricted way when it is needed. If you find a field that needs to have HTML or special characters related to HTML then change the allow-html attribute to support that.
In general I would say no, it would not be a good idea to relax the default security.
Is there a specific place where you have run into this and would like to discuss a change for that, or are you mostly just looking at things generally?
If we do want to consider changing this general policy we should have a discussion on the mailing list and see what people think. If there is a general consensus then we will go with that, and if not we can always vote on it. The best way to start such a discussion would be to write up a proposal and send it to the mailing list.