1) yes you are right, but I thought that this feature could be a sort of compensation for a fully reworked nation like also new and more flags from different county and empires or companies.
2) yes, sadly alts and possibly to change name could help cheater or toxic player but... Since we are talking about ships captains, admiralty could help us with a great idea: the family tree or the line of succession of every single corsair
I think that dev could know how many alts or the old names used by any players. Maybe they could use the AI that is working on Sea Legend missions, and voilà you have for every corsair his history with old pictures names, sons uncles and so on. Sounds funny! Obviously you have that info at high prices a genealogist were expensive