As a developer myself (not an SE one) I see many problems with that specially in the way most systems store the information in back end servers, it might not be difficult for them to add the ' and - but I see some issues if they decide to add á,é,í,ó and ú, specially for stuff like player search, they would have to validate searches for names like "Pokémon" and "Pokemon" which could be the name of 1 guy or 2 different ones.