as pianist who is playing other peopels' music you are a reproductive artistyour aim should be to REPRODUCE the cpmposition as it was writtenthus all the ornaments are a mustif you are not sure if the composer originally wrote the ornaments or they were put in later by sombody else, you should do your own investigation and consult as much sources as possiblebut belive me, with big names like Mozart, it has already been done by other competent musicianI agree that there are on the market some easy versions of popular tunes, but they always bear the sign "simplified version"