Hanuman's flight to Lanka ,in search of Seeta and all events upto presenting ring of Rama ,were carried out effortlessly.without fear and specifically to show how powerful he is being a devotee of Rama signifying enormous strength of God.
Hanuman uprooted all the trees in Ashokvana ,except the one which gave shelter to Seeta. Hanuman destroyed beautiful garden not as a notoriety of a monkey ,but to signal downfall of Rakshas empire,destruction of nishachara evils.
Excepting Seetakruti's shelter tree , all were uprooted; only those works, which give shelter to Shastras and its teachings ,need be nourished else all has to be uprooted ,this is acceptable to Vayu and such works give immense pleasure to God.
Ravana's Ashok(without grief) vana turned into Shok(grief) by hanuman, but it gave pleasure(ashok) to Devatas. For those who oppose hanuman, even all the pleasures of the world also bring grief, at the same time his devotees enjoy all the pleasure even in grief (samsara). Every work of hanuman,explicitly does dual work of blessings ,removal of misery for devotees and extreme grief to those who sin .This is all done as a service to Rama(vishnuprithyartham) only and not out of some mischievousness(natural to monkey) but out of enormous knowledge and as Bhagvat Dharma.