Abenomics was not likely a good idea at the time nor in retrospect, but a lot of the GDP contraction has less to do with monetary policy and far more to do with cultural/social policies that the population embraces - government-sanctioned or not.

Very low birth replacement rates, very strict immigration laws (basically anti-immigration RE: chances at citizenship), long history of nationalistic behavior regarding homegrown consumed goods rather than taking advantage of trade economics of scale, Sony et al being beaten by Intel to the correct Silicon Valley model, and so forth all contribute to contracting GDP quite a bit.

EDIT: This is not to say I think Japan has the wrong idea or whatever; I agree that chasing GDP is not some end-all be-all thing. I'm just saying that while I don't regard Abe as a genius economist, I don't think it's too fair he get a ton of blame either given that his country's demographics, social model, and other factors likely contributed far more towards the inertia of a shrinking economy.