Plus it gives me local public transport bus/underground trains/ferries/... in most major city areas. There are reserved spaces in trains and I can use the DB lounges where available. Also you can take your children with you for free in trains.
Another plus, which I haven't used: you can send you luggage (max 30kg) for free on workdays home to home.
For example if I work in central London again my season ticket for a 65 mile journey (bedford to London) is over 6000 euros a year.