Its more complicated than that. The fact Peter Tatchell and other gay people (like myself!) agree with the ruling shows that.
The fact is, refusing someone because of who they are is illegal, as it should be. But you should not be able to compel people to perform a specific service they don't want to. Gay bakers shouldnt have to make a cake saying "All gay people will burn in hell". Or make giant cock cakes. Or anything else.
As much as we might not like it, religious beliefs are a protected characteristic in British law. And even if they weren't, I fundamentally believe you cannot compel someone to provide a specific service contrary to what they want to do.