Is it fair to organize conferences in beautiful tourist places?
Fairness is not a point at all in the organisation of conferences. The goals of the organisers of an event (scientific or not) is to have as much incentive as possible for people to come. 
Indeed, most of the time, the organisation part has to be done before knowing the exact number of attendees, and the organisers still need to cover the expenses in terms of room rental, catering, etc. There are many ways to attract researchers for a conference: 


Organise a high quality conference, where the scientific interest alone make it worth to come. 
Select a "paradise" location, such that the attendees can just show up for their session, and then relax on the beach or on the ski slopes. 
Select an "interesting" location, where people wouldn't go normally in vacation, but that could be a good opportunity. 
Select a quiet place, with few distractions, allowing the attendees to focus as much as possible on work. The Dagstuhl seminars are quite famous for that. 
Select a conveniently located place, such that it will be easy (and cheap) for many attendees to come. 
Select a "cheap" place, for instance by organising during summer in a university, where you get the rooms for free, and where housing can be cheap. It can be a nice way to attract many students. 


Clearly, in general, it's a mix of those, and you can't maximise all of them. And then, as aeismail said, it's a matter of whether you can get funding to attend the conference. But the question of whether is fair or not is not really relevant. 

EDIT: I have rephrased the answer following David's comment. Clearly, an important point is that there is always a targeted audience for any event. If you want to organise a conference on an extremely specific topic, maybe there are only 20 researchers who could be interested. The job of the organisers is therefore to find the best way to attract as many as possible from these 20. I also want to make the difference between the reason behind organising an event, e.g., advance science, create collaboration, make money (for some scam conf) and the goals to reach in terms of organisation.