Originally JBLU had same legroom as most carriers. United came out with additional legroom in some rows and American added MRTC (More Room Throughout Coach). JBLU, unlike Southwest, has always branded itself as offering high quality service. So they matched extra legroom of some competitors with additional legroom in most rows. The irony is that American is removing extra legroom and going back to original legroom. Jetblue now leads the industry with its extra legroom (United still has more legroom on its mainline flts in select rows but this is only available to select passengers).

There seems to have been a few technical reasons for having different legroom in the plane. The first 10 rows are before the exit row. They did not want to remove an entire row before the exit row. They removed a row after the exit row and the saved space was given as extra legroom. This also allows them to fly on some of the longest routes for 320s without having to have multiple 320 configurations.