In the end, the problem is that people don't, actually, need more money. There doesn't seem to be sufficient demand for money, even cheap money, so as to print enough of it to cause inflation. We come to a point where assets are preferred over money. QE tries to seduce asset possessors to give them a nice bonus to trade it for (inflating) money.
You got this wrong. There is too much demand for money, i.e. keeping cash reserves, not too little. The central bank is successfully selling the money (Buying assets) but the recipients are just keeping the cash, not spending it.
Maybe you meant people don't, actually, need more debt. They are not going to banks for more debt and then investing for a positive return. The reason is they look at growth and see none. No one wants to borrow and invest if the economy is stagnant.