Therefore it seems reasonable to require that there should be a certain visible improvement to the world if Buddhism benefits all sentient beings.
Certainly, there is improvement when the teachings are applied. However, that doesn't mean Buddhists can twist people's arm to practice the Dharma in the societies we traditionally hold a majority in.
The Buddha taught a lot of things. A lot more than a single point about Mahayana's stated objective can address.
I can only give you a Buddhist response and you can accept or reject it. This will be rather lengthy for what I'm used to giving.
First off, the Buddha was realistic about the nature of being an animal. That humans are animals means we have capacity for bad. Our own faculties are sometimes the very leashes that lead us on. The Buddha's diagnosis of the human condition was not idealistic. Indeed, I won't mislead you about it.
The Buddha's diagnosis of the human condition was rather bleak. He acknowledged we are beings capable of destroying ourselves. It is not the Buddha's fault if we do so, seeing as his teaching is now known in virtually every corner of the globe.
The Buddha has told us that anger, hatred, and greed are destructive. We know that the Buddha and even great teachers of other world religions have said these things. We choose not to listen. We choose what parts sound easy to us, and even Buddhists can be guilty of that.
However, the Blessed One wasn't offering a buffet line to pick from at will. He was offering a total explanation of where humans stand and how dire our situation is. When we disregard things he taught, even Buddhists- and decide what parts of his teaching we can simply reject> we do so to our own peril.
The Buddha gave the teaching and there is a certain aspect of responsibility on the part of humans. However, we're only touching on the human aspect.
What I will now proceed to say is the belief of only some Buddhist schools. However, it is my belief, and so I do right to speak about it. It is the belief of the great Mahayana vehicle, and it is the hope of all Buddhists- even the Theravada vehicle.
The Buddha was not an ordinary man. He was born to become a Buddha. In the view of some Mahayana schools including mine, this means he came from the Buddha lands of Nirvana. He is not an ordinary being.
Buddhists leave things as paradox where we cannot possibly describe them in human terms, which is good- since human terms are just that. It is an entire mystery for us how the Buddhas are truthful projections of the sum reality of Nirvana, but I believe and accept the teaching that they are.
Shakyamuni Buddha is like all Buddhas. In him we could see Ultimate Reality reflected. He spoke with the boundless wisdom of the Dharma storehouse of infinite merits. The Blessed One, and by this we also mean that Cosmic Buddha that Shakyamuni reflected in the world> the Blessed One will not let those beings he came into the world to save be ultimately lost.
The Lotus Sutra central to my school teaches a great hope. That the Buddha will at the exact right time save all beings. He can do this because the Dharma is called a storehouse of infinite merits. For reasons going beyond human understanding, the Buddha does not save all beings now. Rather at present, he works through his practitioners, and generates Bodhi fields through us when we act according to the virtues, called the Paramitas in Sanskrit.
The Buddha was not ignorant about the human condition and how prone to delusion we are. How entrapped we can be in our habits and emotions. Unfortunately- has the Buddha's Dharma been perfectly practiced in those countries it reached? No it has not. It has even been joined to political causes like Japan joining the Axis powers during World War II. Buddhism has nothing to do with that, so where the Dharma has been ineffective- this is not because the Dharma is lacking.
When the Dharma has been practiced, the nations it reached thrived. They had peace, great intellectual and philosophical revolutions, and the rulers were just and cared about their people. When those countries departed from the Dharma, the fruits of the Dharma naturally vanished.
Japan and China today are far fallen from the Buddha's Dharma with their pursuit of materialism, consumerism, and profit. This is indeed sad. It is sad to see the degeneration of the Dharma, that the Buddha knew all too well would happen.
I dedicate the merit of my practice everyday to the hope Japan, China, and so on will abandon what the west taught them and return to the Sublime Dharma. I also pray that the west will embrace the Sublime Dharma, which may be the ONLY thing that can save our world from being destroyed by empty consumerism and corporate profiteering.
I am sorry if this seemed preachy on my part. This is what Buddhism historically teaches.
Historically not personally. I did say I was only distantly acquainted and did not claim the last word on the subject, but I think its reasonable to ask where are the results, the change, the improvement. If people are being improved then this should be reflected in the world. Is it so much to ask for from an enlightened being such as the Buddha?
I answered this largely above.
It seems to me that Buddhism attempts to appeal to the whole human both the evil and the good by saying that it is about escaping from Samsara, but if the end result is believed to be compassion then lets not kid ourselves what its actually about.
It is ultimately about both, and as I said in my first post- the traditional view of Mahayana is both will happen.
Again, it seems to be about being nice.
There's a reason I tend to shy away from emphasizing Buddhism's niceness
@Brickjectivity. I don't want to encourage any of the secular distortions of the Dharma taking place, and many secular Buddhists think the teachings only 'sound nice'. They aren't serious about the teaching.
There's a story on p. 129 of this Google Books 
