I suppose it depends on who's in the mix, as it were. But I definitely see more concern for and awareness of the impact of travelling abroad for holidays than this survey indicates.
I don't know many of the 'middle class' would be travellers some are referring to, and I don't think environmental awareness is a class thing? That sounds a bit crass. Most of the people I know can't afford to holiday abroad on a regular basis, but are still concerned about the environmental impact of the one trip they might consider every few years.
In my own small sample group there are a few different categories of people, who still overlap in their "I know this isn't ideal..."-thinking about booking foreign trips for leisure: quite a few like you, Weeping, who are already making lots of environmentally motivated choices in other areas of their lives and who, by all accounts, could probably be said to already be doing 'their bit'.
I work in a school, so colleagues tend to be naturally concerned about the futures of children, hence feel guilty about making decisions that have a negative impact on the environment -many have taken no-flying pledges- but some choose to fly occasionally and usually express ambivalence about it.
There's definitely an element of cognitive dissonance about flying on holiday: the impact is incontrovertible, but simultaneously not noticeable here and now. But it's not just flying; tourism isn't sustainable in many popular locations, and has had a really negative impact on local communities and environment for a long time.