Veer Ji I think it depends on the situation. If some commits a bajjar kurehit or any other major sin then they should weep. If someone passes away or something bad happens then one should make efforts to accept Guru Sahibs will and not weep.
crying helps to cleanse...depends on the reason behind it. don't think it is not allowed, everyone is different. sometimes we are weeping in our hearts but no tears show.
Only blessed ones cry in the love of Vaheguru. Only blessed ones burst into tears when hit by the arrow of Guru Sahib's Shabad. At the same time, as far as worldly dukh is concerned, Sant Jarnail Singh Ji Khalsa Bhindranwale in his conversation with Vishnudevanand said that GurSikhs don't cry like others, stay abide by bhaaNa.