Well, let's compare razors with shoes, back in the old days people only had a pair of shoes, today for many reasons we have plenty. In terms of utility one pair would do the job, however there is a large amount of different ocasions, where just one pair wouldn't be enough, the only pair you have wouldn't comply with your specific needs, your spirit of mind of that particular day. Therefore having more than one pair of shoes became something regular (not considering the aspect of prices of course). The same goes for straight razors, although all razors are meant for the same purpose - shaving hair - each one performs differently. That's the base of my decision making process regarding straight razors, or I could just say this is the way that I justify to myself why i need more than one razor if all of them attend to the same purpose.