Doesn’t the replacement of bunkers with grass swales make the course easier?

There is no definitive answer to this question, a poor bunker player will say “Yes”, a good bunker player may say “No” depending on the quality of their short game. The overall aim is not to make the course easier but to present a variety of challenges and to not reward poor shots with ‘lucky’ bounces onto the green. A shot played towards a swale is likely to stay in the swale. In some cases the swales also provide definition and help the green to stand out more, as is the case with the 18th green.
The Competition and Handicap Committee compared playing statistics for the 10th hole for the year before and the year after the swales were constructed, and found there was little change in the average score.