Part of me strongly wants them to be locked to certain domains per god, or at least locked out of "opposed" domains.
But then there is the nagging part of me that feels that unlike 3.5 that had lots of domains, 5e only have a short list of them. And it's very likely that if Larian has to start choosing subclasses to leave out it will be the cleric (and wizard) specializations that go first, so we might end up with even fewer. So if there's just a handful of them to choose from... It just feels less right to restrict them.
The best solution is probably to make the option to de-lock domain restrictions as we do with appearance options currently, as somebody suggested above.
