No they are not -certainly not in the secondary location street in Dublin 1 where I own a shop.
I and my fellow commercial landlords are happy to get a tenant at all.
In primary locations or top shopping centres -three months rent in advance is common, but not three months deposit as well (unless,maybe, the tenant has no track record at all).
Actually many landlords are offering incentives to get tenants - one or two free months.
If the tenant is first time tenant and/or has no strong commercial record AND the property is much in demand then either the four month rent Or a security depsoit with a months rent is acceptable. Not both.
It's not the actual money per se that would worry me as much as the fact that the landlord may be one of those greedy unreasonable ones that could continue to make tough demands.
I wouldn't worry about the landlord going bust. Once the tenant is in and can show he has a lease and is /has paid rent it would be almost impossible for a new owner to remove him. Important that any security deposit is written into a contract as being an equivalent to rent in the case of any problem.