As to the first paragraph, the formulation for the British warships "were built to fight" helps create the impression in a reader the French ships were not so intended given the "there remained important differences, however, between British and French warships". I believe both French and British ships were built to fight.
Then your quote is an example of how Roger does not give a fuller analysis.
To stay with the first paragraph, for example, he leaves out exploration of the interaction between "somewhat smaller in tonnage and shorter" and "more heavily timbered". The implications of a limited supply of better timber might have been explored. Given the type of oak timber and the annual needs for both building and repair, a limit on ship design arose in practical terms.
The "built to stand the strain of prolongued sea-time at all seasons" is a throw-away line. It is not inaccurate as that was the intention, yet reality gets in the way, consider only the problem in ship duration the Royal Navy suffered.
As Pering wrote about the Royal Navy in 1812 (see link), "By the present mode of ship-building, that noble structure, a first- rate man of war, becomes useless, from premature decay, in Jive or six years, and the average duration of the navy itself may be said to be limited to eight years,—a shortlived existence, indeed, when we reflect on the immense expense and importance of our fleets. This is no light assertion, (as incon- testibly witness, in the former respect, the Bulwark, Foudroyant, Ocean, and Queen Charlotte), and it completely oversets the general idea, that ships built in the King's yards are better and more durable than those built in private ones, except for workmanship."
Then the second paragraph has similar "point of view" issues and shallow analysis. The final "death trap" statement being a combination of both.