The issue is a supply side problem. Messing in the market will result in less landlords, less properties available for people and less supply. This will mean greater demand and drive rent prices higher again.
A rent freeze will protect renters in houses now, but what about new renters, people moving to dublin to start working, where will they go? There simply won't be any properties for them to rent or move into. This will hit employment and slow investment. When that happens, it doesn't matter about anything else. It's the economy stupid. If the economy isn't going well, there's no money to do anything. Period.
Landlords charging €2,500 a month for a three bed-semi is a disgrace and I say that as a landlord. Accidential one at that in negative equity. Who decides what is a fair rent to charge? If the government decides, do you not think that private owners and investors will up sticks immediately and leave for fear of interference, state control etc? Of course they will.
Due to a tax change on rental income some years ago (all liable for PRSI and USC) rent per month had to increase by 22% just for landlords to be left with the same money as before this tax change. Rather than the government penalising and hitting landlords consistently with red tape, legislation, rent freezes and making them out to the villian, why doesn't the government reverse the decision to make rental income liable to PRSI and USC and in return get landlords to reduce rents by 20%. Landlords are left with the same money, renters get a 20% reduction instead of the 1500 euro or (maximum of 8.5% reduction as per Sinn Fein manifesto) and that's real action there. But they won't. They will hit landlords and drive more out of the market.