May be your personal opinion, but especially the Orléans are in different cases connected with the daughters of Louis XIV by Montespan: As far as I know it, the sun king, who had seven daughters by the Marquise de Montespan and three by Louise de la Baume de la Blanc, married Francoise Marie to Philippe II. of Orléans, and Louise Francoise tp Louis III. of Condé. Louis Philippe does not only descend from the daughter Francoise Marie, but also from the sun king´s son Alexander, who had the son Jean- Marie etc etc. I think it was common to marry the illeg. to the official lines of the family. I have read that the sun king legitimized almost all of his children from his lovers, and gave them an official status and title. He also lived with those children together in his palaces. It´s obvious that Ludwig´s children by his mistresses had a much better health than the children of Louis by queen Maria Theresia. A possible reason for this might be the close familiar blood relationsship, because both had the same ancestry of the Spanish Hapsburg line: Maria Theresia was the daughter of the Spanish king Philippe IV, whereas the mother of Louis XIV was one of the sisters of the Spanish king. And not only that: The mother of Maria Theresia was a Bourbon, Isabella, the sister of Louis´ father.
So many children died in early age: The genealogy shows that of six children only the "Dauphin" survived childhood. So Louis had much more luck with his other children from his mistresses and took him in dynastic marriages.
As a matter of fact it was a form of humiliating his royal cousins.
Marrying his cousins to bastards (even his own ones

) was a form of downgrading their houses.
The Orléans were always a menace on Louis XIV's throne.
And the Condés, although much more calm in this period, caused severe trouble at the beginning of Louis' reign.
As they say "revenge is a plate to be served cold".
Louis , quite machiavellically, decided to stain his cousins lines with the stegm of illegitimacy by marrying them to his illegitimate daughters.
His sister-in-law, the proud Liselotte of Pfalz, the only one who had the nerf to face the king, was appalled when she discovered that her only son, Philippe, the Regent, was forced to marry Françoise-Marie.
She did all she could to stop such marriage, but Louis had traced his plan and nothing nor anyone would deterr him.