She did the best she could, anne. She became baroness but the practice has been that the son of a baroness, countess etc does not inherit the title of baron, earl etc. So the only way to give a hereditary title to the family was to give one to her husband. He could have been given a higher title, as the former Speaker,George Thomas, who became Viscount Tonypandy, was, but that would mean he held a title of her higher rank than hers. And the idea of having Mark a Viscount certainly would not appeal. Viscount Tonypandy had no heir , so succession did not present a potential embarrassment nor was there the prospect of his descendants being eligible to sit in the House of Lords.
(Clement Attlee was made an Earl. That does seem odd, considering he was a Labour Prime Minister and Churchill had refused to be elevated to the peerage).