You have just defined a stream entrant!
Yes, jhana is good. It helps for the reasons you mentioned. A 'dry insight meditator' (never met one who hasn't with time accidentally gone into jhana
) if he continues with the practice in an unbroken manner should not have the problem of craving. However sometimes vipassana insight can become distanced from 'reality' and even though people maybe fantastic in their meditation, when it comes to the real world- their cravings are intact. I find that yonisomanasikara might bridge the gap in those situations. They also need to have firm grounding in right view (four noble truths).
However jhana practice blocks my thoughts too much during the waking period. So I have stopped doing it. I am experimenting with mindfulness filled with saddha, sila, compassion and dana- similar to the one recommended by the Buddha to Mahanama. http://www.accesstoinsight.org/tipitaka ... .than.html