Absolutely it is not ok. The Robin Hood idea isn't the right way to think.
Stealing is a crime even though you are taking from someone who may have more than you. It doesn't make it any better either by saying you are giving it to the needy. Life is hard enough to make a living without it being stolen.
There are a lot of charities who have wrecked this idea as the money donated doesn't end up at the promised place. Most charities are funded by large donors and normal people who do normal work. The problem is the admin and directors of the charities have to live a normal life but it is a ruse.
They are living off donations and are living the high life and is no different as they are stealing under a false pretense. the ones who suffer will suffer more as the donations will stop altogether. This is a modern day Robin Hood that takes some of the rewards.
Morals and ethics need to be applied to this idea and it just isn't right whatever way you look at it. If you want to make a difference then do it the hard way and collect donations and in an organised way donate to the needy. i have stopped giving to charities as I don't trust them anymore.
In South Africa you can lease a blind man to collect money at traffic lights. criminal gangs are doing that so who do you trust anymore. If I see someone down and out I will buy them some food but otherwise my money stays in my pocket. the days of receiving hand outs have long gone and the needy are suffering because of this.