Whatever the "real" average fare was for 1990 in discounted terms in todays money it is still huge. A quick google search will reveal that wages were incredibly low for the average punter.
Until they solve the problem of Ireland being stuck on an Island then a lack of competition will inevitably result in the fare paying public being at the mercy of FR and the like should a monopoly be allowed to occur.
In present day terms you can see examples of what a monopoly might look like. Flights for the Euro championships priced sky high, flights cancelled and then reinstated at double or more for the Heineken Cup as someone in the back office messed up when preparing the original schedule.
In terms of FR the witholding of his landing fees for months due to a spat with the DAA over floor space in T1 in Dublin a few years back highlighted the nastier side to MOL. The judge in that case said that the actions of FR were "wholly disproportionate". In unfair employment cases the judiciary have even called his management dishonest.