Being the sort of person who dips into encyclopedias randomly for fun, I do read glossaries; but I don't expect other readers to be like me.
But does it really matter how a reader pronounces a name in their head? Off-hand, I can think of only two circumstances where clarity may be required:
- Where a plot turn is based on a character's misunderstanding of a name; this would baffle the ill-informed reader, but then I'd expect the author to rely on more than a glossary to let the reader in on what's going on.
- A joke or pun, which is a rather poor reason for a glossary entry, don't you think?