The A319CJ does have this option, but as far as i know no other A32X, or infact anyother AI aircraft have this option. The problem with the A32X aircraft over the 73X aircraft is that it's a lot taller, therefore any integral airstairs will be longer, larger, and therefore heavier and bulkier, which is bad.
Maybe, but have you SEEN the integral airstairs for the A319CJ? They're HUGE! Those things must be very heavy, and take up a lot of room. The A32X's height is a big disadvantage to potential low cost operators. Not only do they have to have a airbridge, or seperate steps, but they can't just open a cargo door at the last minute and chuck a bag or two on.
Actually, airstairs are available not only for The CJ, but for the entire A320-family. My operating manual has one of those many "intentionally left blank" pages with the title "airstairs", as we don't have them installed.