Simply put - you are not your music. It is an extremely fallacious and dangerous thought which has lead some fine leaders such as the Nazi's to deem Mendelssohn "degenerate" art, the former USSR deem many composers betrayers of the party who deserve the camps, or Peter Phillips who supported the Catholic Church in England by writing music for its liturgy at a particularly bad time and was imprisoned. The mistake made was when leaders saw these composers' musics as somehow representing an "object" against their state rather than a complex person who may or may not share the state's ideology.
However, although one is not their music, one cannot separate the impact various parts of their lives have upon what they produce. It is just a slippery matter of what compartments of their lives may have had influence upon their composition. Broadly, where you live, how you are raised, what you do and whom you spend most of your time with, all influence the act of composition. As to your "willpower" , a more palatable intellectual position is what role their music composrs thought it had in society. For Mahler, each of his symphonies were his own personal sagas in sound - and an exploration of the orchestra's timbral possibilities - plus he had at his disposal a top flight orchestra to conduct. Wagner's music was in part an expression of his nationlistic pride and also a more altrustic motive to develop a classical music better connected to German mythology and history. Bach wrote a majority of his works for the church to serve a very specific function and to understand the motivation of his works requires a good solid knowledge of Lutheranism. Beethoven was incredibly influenced by the philosophy of the French Revolution --- but also was very much a working musician - he wrote for the crowd in part - albeit a wealthy crowd who supported his explorations. For these examples I skim only the very surface.
If this is what you mean it is not viable to compare one composer to the other, rather the arena to look is a history of aesthetics. But again a composer is not a music filled spirit who comes down from heaven or hell or whatever netherworld to dispense his aural beautitudes. No, a composer is a human being who happens to enjoy writing music. He or she enjoys it more if they are paid for it. Once you realize that, you may see how vacuous you opening thread reads.
Possibly, you need to look at the aesthetics of music in one specific area - what has been considered the predominant function of music through a particular epoch? I raise this as your division between the Baroque/Classical composers and the Romantics does point to a manifestqation of a change in aesthetics due to a transformation of what society considered the main functions of music - a transformation one can point to starting as early as the late 16th century.