Rat5
You make valid point but within the service sector there has always been differentiated prices .
Go to Paris and visit a Cafe, stand at the bar, sit inside or sit outside and you will pay a different price.
Book a Holiday inn and if well in advance it can be pretty cheap but again depends whethers its weekend or weekday, book a Travelodge and it can be very cheap but non flexible or expensive and flexible.
Go to McDonalds and order a burger and they will suggest a meal, order a meal and they will suggest upsizing or a dessert, you can still have your basic burger but the stress the value in Big Mac Meal.
Restaurants add in service charges be it for only 1 person or for large parties and often on Weekend nights they will not have a table for a singleton as minimises revenue.
Pubs do it as well with pensioner specials or a cheap specials board during the week at lunchtime and more expensive meals in the evening or cheap beer during the week and not on Friday or Saturday night.
Airlines are just doing what the service sector has been doing for years in realising if you break every single activity down and looking at whether its a cost or revenue earning opportunity then you can decide how to run your business.
FR in fact are offering people menu of so many items and getting people to make decisions on what they want to add.
Many of the charges FR have imposed have been picked up by other airlines and tailored to their own requirements.