The Pros have already done their serious professional competing against each other and got their national or international titles to show for, so I don't think they need to go through all that again just for our benifit. Strictly is a time for them to compete in a fun way and get an opportunity to pass on some of their years worth of experience to someone that has never competed professionally in their field at a top class level.
If you want to see serious Pros competing then you can get down to a major competion somewhere in the country, I think some let in everyday public members (prob at a price). But I don't think the Pros want to sqaure up against each other on here, hence why they do Strictly where there is a celeb involved which decreased the intensity of real life professional competion. Otherwise if they wanted to be back in a serious-type of competing show, they can do SYTYCD (or another format like it) where all the contestants are already dancers competing and showcasing their skills for airtime and whatever they get off the back of it. Some of the pros on this show have done SYTYCD already.
Personally I'd love to see more Pro numbers on the results show, but I presume we can't because where would the Pros get the time to rehearse more numbers (alongside training their celebs too), and also the Beeb can only show so much of the show otherwise they'd prob fear SCD overload if they take up too make collective hrs up during the week.