Sure, if you are happy living like a student. If you want to own a place in a reasonable part of town? If you want to be able to have a child? If you don't want to have to rely on two incomes to pay the mortgage? I didn't say it wasn't possible to live on that, only that that kind of salary was table stakes in those cities i.e. it's adequate but hardly living like a king.
Personally I can think of a plenty of other places I'd rather live in where you could truly live well on that kind of money.
Source: I live in the first of those on a similar salary.
There's a world of a difference between living like a student and owning property in a reasonable part of Dublin/London. a €45,000 salary (which is roughly $50k) is definitely a comfortable, non student lifestyle. It's not going to buy you a decent house in Dublin, but it's a comfortable lifestyle, and more than adequate.
€45,000 does sound a bit low. I lived on €40,000 (after taxes, rent was only 8-10% of the yearly income) in Croatia and lived like a king (travelling, restaurants, buying stuff without worrying about the price, massive amounts of good quality food).
Moving to any other major European city would require me to at least double the income to maintain my standards.
Personally I can think of a plenty of other places I'd rather live in where you could truly live well on that kind of money.
Source: I live in the first of those on a similar salary.