Keyword separator limitation not backward compatible

Somewhere along the line, Lightroom imposed a new limitation on keywords preventing the use of either commas or spaces in keywords, because they now say commas or spaces are used as a keyword separators.  (What was the separator character when these characters WERE allowed?)

For years now, I have created hundreds of keywords using both commas and spaces to tag people by last name, first name and towns by city, state.  Do I now have to manually change all of those keywords to eliminate commas or spaces?

I would like Adobe to add more keyword separator options.  For example, "." and "/" can be treated as keyword separators when reading metadata.  Why are these characters not allowed as separators for keyword entry?