There are myriad reasons for exchanging pieces, as you say, for example, to break up a Bishop pair, to gain initiative, etc, so there are many tactics and strategic plans connected with exchanging. A lot of times there is a better maneuvering move compared to the easy way out by exchanging. Karpov once said that early in his career, he exchanged all his pieces thinking he would eliminate the danger of his position only to end up in a lost endgame! Your on the right track that there are legitimate reasons for exchanging, and you definitely don't want to exchange just because your afraid to deal with so many pieces on the board!
Is exchanging often an amateur strategy?

I have heard of top players who liked to exchange a lot and simplify the position. I am the same. If my opponent has created an unbreakable barrier the best thing is to force him to exchange. Sometimes it is not possible though, and then I ask for a draw. The reasonable ones take it, clearly we are not going anywhere
okay, so chess can be played in sharp lines which favor tactics more and also on quiter lines which favors positional play. What I do not see too much in master games is quick exachanges (they have 20-25 moves for a non pawn exchange often). However, as a lower ranked player, after I have set up the pieces quite good with positional pieces, I look out for exchanges, with few principles like breaking bishop pairs, cental knights protected by pawns, and more central space. So is this a quite good strategy? or what is especially wrong in this? thank you. :)