I agree with the sentiment, however as regards George's siblings, I think that would be not great for immediate family relations (I am not talking about cousins, just siblings). After all, whilst you could argue that Charlotte or Louis could choose, as adults, to be working royals and gain the Princess/Prince titles for themselves, in the case of George, it is pretty much defacto. He is the firstborn heir and will definitely be the THE Prince.
It is known (as expressed in his own words) that Harry keenly felt that he was treated differently to his brother the 'Prima Donna' future King in waiting, so to speak. Can you imagine hearing your brother being told 'oh you're going to be the Prince one day' and then reading stories about princesses growing up, but mum and Dad are King and Queen but you don't have the title of Princess or Prince unless you work for it, but big brother will for certain be a Prince and everyone is deferring to him and treating him like a Prince already anyway.
So I think only the very immediate heirs of the King should continue to have titles from birth.
Everyone else no. Not even if they become working Royals. If Archie or Lillibet decide to contribute to the UK Royal institution in a meaningful way as adults by performing duties, they still don't get titles, they can be Lady or Lord. They have other titles...perhaps they can use those. That way we ensure they are not becoming working Royals for personal gain and flexing the titles for leverage. It is clear the 'Apex' titles (Prince, princess, duke, duchess) confer a lot of soft (if not hard) privilege.
In the case of A&L I personally think having titles has the ability to confer more harm than good as they live in the USA, and the USA is about commercialising and capitalising on whatever advantage you have, it's both good and bad. Americans are very positive about success, but on the other hand they can exploit anything akin to celebrity to the max. And they are enamoured with Royalty. That could be hard for A&L to negotiate and come with temptations, and they are not in the UK to understand what it really all means in practice.
So why allow it? Edward and Sophie have clearly projected themselves forward in time and thought about things like the media exposure and giving their children privacy and have not conferred titles upon their children, which is prudent.
I frankly do not understand why Charles did not make limiting titles a key legacy aspect of his reign. I'm sure newspapers were saying he was keen to do this before he became King, but then it seems to have been dropped. He seems to not be thinking long term about this, but now that both B&E seem to be exposed by their own financial improprieties, it would be a good time to enact legislation.
I guess you could argue that it might reduce the glamour and hasten the decline of the RF. That might be what he is thinking.