One of the many reasons I pay extra to travel First class is that it significantly reduces your chance of being near to 'undesirables', eg dunk party goers, singing football hooligans, uneducated delinquents often shouting out appallingly vile language, etc etc. The late night weekend services from Edinburgh to Glasgow are particularity bad, especially on the Bathgate line. Don't get me wrong it is only a minority of people who cause problems and most standard class passengers are absolutely fine, but by paying extra for First you certainly reduce your chance of being next to these 'undesirables'. This is one reason why if I'm treating my partner to a romantic weekend or even just a pleasant day out I will always try to go First class. If First class didn't exist I would simply take my car instead.
I also find First class passengers tend to dress smarter, indeed if I am traveling in First I will make more of an effort to look smart than if I were traveling standard, not that it bothers me if First class passengers wear scruffy jeans etc. I think there will always be a whiff of the British class system when traveling First class. I guess one could compare this to an expensive health club vs a council gym, both do the same thing but attract different sorts of people. Personally I think it is something we should embrace rather than be embarrassed by, just look at the popularity of our aristocracy, monarchy and programmes like Downton on the world stage. Many people almost expect First class travelers to be from certain sectors of society. Perhaps Virgin trains could rename First class to be more in line with Virgin Atlantic, Upper Class! On a serious note, First class has existed since the start of passenger railways and is unlikely to go anytime soon, judging by its popularity.