The previous verse is relevant:
or you may say, "If the Book had been sent down to us, we would surely have followed its guidance better than they did." There has now come to you clear evidence from your Lord, and guidance and mercy. Who, then, is more unjust than one who rejects the signs of God and turns away from them? We shall requite those who turn away from Our signs with a painful punishment, for their turning away. (157)
Note, aya means sign, ayat means signs. Allah (swt) says that the ayat have arrived, the signs have arrived, what else are the rejectors expecting? If they did not and do not believe the signs that have arrived already, then anymore signs will be useless.
This is related too:
“This day, I have perfected your Deen for you, completed My Favor upon you, and have chosen for you Islam as your Deen.” (Surah Al-Ma'idah, 5:3)
Islam is complete, Quran is complete, all guidance required is there. There were signs for people in the Quran 1,400 years ago, and 1,400 years later there are still signs that attract people towards it. The guidance, information, facts, everything you need to know, information that leads you to success in this life and akhira (afterlife), all of that information is available in the Quran.
If Allah (swt) revealed Angels to us, what difference would it make? The rejectors will probably begin to worship the Angels like they are worshiping Jesus.
Why did the prophet then come with miracles? The prophet's didn't come with miracles to compel people, rather to test who believes and who doesn't after compelling signs have arrived. There are many historical events mentioned in the Quran, where the people have rejected prophets, so miracles aren't suppose to compel people, but to test people.
This life after all is a test, and what is the point of a "judgement day" if there is nothing to judge you by.