Reasons For Continuity Of Prophets In Past
Mostly the political matters of bani Israel were run by the non prophetic persons. While the prophets were there to guide and warn. Bani Israel faced such circumstances that they lost their book. They were exiles and subjugated for a long time. It was due to the circumstances that their book was not preserved in its original language, let alone inzar which couldn’t be save even the one done by Jesus. Then came through Qur’an and we see it was preserved. Shariah and inzaar both are there. So there is no need of any prophet further.
You are suggesting a whole new scheme to God. God didn’t do that. This is his scheme what we see. He operates within the circumstances. If He plays miraculously all that way, the scheme of test cannot run. If his message stayed when circumstances didn’t allow it would be a miracle which would end that test of believing. No one would have an excuse to disbelieve.