I don't agree, because the situation of Anne and Edward is not the same.
Edward chose not to give royal titles to his offspring, even though they have the right to them
Anne could not pass on royal titles to hers because it is barred in the female line.
So a solution whereby all DGC get them, but the convention is that they are not used other than in the direct line is a possibility. Or going further and only having it given to those in the direct line in the first place.
But it the first two Wales DC had been Georgina and Carlo, under the current LPs, the DC in the direct line would be Master and Miss (or Lord and Lady if Georgina married a peer) whereas those in the "spare" line would have the right to be HRH Prince/ss (as would all those of subsequent sons, but not daughters)
It's a wrinkle consequent to the abolition of the "male" part of primogeniture, and I think it needs ironing out (ideally before any of the young Wales are coupling up)
Edited to add: it need not make any difference to the Sussex DC, if it were stated that all styles and titles based on the LP in force at the time of the person's birth could continue in use. So Beatrice, Eugenie, Louise, James, Archie and Lili all keep the right to be HRH Prince/ss, but can choose whether or not they use it (though HRH is of course now in practice for working royals only); and none of those 6 will be able to pass it to their DC.