The benefits of morality are many.
According to the Buddha, the main purpose of morality is non-remorse (AN 11).
Or, there are five benefits, including attainment/guarding of wealth:
“Householder, there are these five benefits
for the virtuous in the perfecting of virtue. What five?
Here, householder, one who
is virtuous, possessed of virtue, obtains a large fortune as a consequence of diligence;
this is the first benefit for the virtuous in the perfecting of virtue.
Again, of one
who is virtuous, possessed of virtue, a fair name is spread abroad; this is the second
benefit for the virtuous in the perfecting of virtue.
Again, whenever one who is
virtuous, possessed of virtue, enters an assembly, whether of khattiyas (warrior-
nobles) or brahmans or householders or ascetics, he does so without fear or
hesitation; this is the third benefit for the virtuous in the perfecting of virtue.
Again,
one who is virtuous, possessed of virtue, dies unconfused; this is the fourth benefit
for the virtuous in the perfecting of virtue.
Again, one who is virtuous, possessed
of virtue, on the breakup of the body, after death, reappears in a happy destiny, in
the heavenly world; this is the fifth benefit for the virtuous in the perfecting of
virtue”
-- DN 16 (Nyanamoli, trans)
The Milindapanha also gives a nice description of the virtue of a moral individual:
"A moral individual, great king,
is like an antidote in destroying the poison of defilements;
is like a medicine in curing the sickness of defilements;
is like water in taking away the dirt and mud of defilements;
is like the jewel treasure (a gem said to grant wishes) in bestowing all attainments;
is like a ship in helping beings go to the far shore of the four floods;
is like a caravan-leader in helping beings cross over the wilderness of birth;
is like wind in extinguishing the threefold fire and heat;
is like a great cloud in replenishing the mind (as with rain);
is like a teacher in causing beings to train in wholesomeness;
is like a good preacher in causing beings to see the path to security.
Morality is considered to be the foundation of the holy life, along with right view (SN 47.3).
As Buddhaghosa says,
Dare anyone a limit place
On benefits that virtue brings,
Without which virtue clansmen find
No footing in the dispensation?
-- Vism I.24 (Nyanamoli, trans)
As for needing incentive, sometimes it is important to distinguish between moral precepts and actual morality. Keeping the precepts is important, as it serves as a general frame of reference in corralling the mind, like fence posts. It is not enough, though, and the mind will still tend to rebel against the precepts if one does not build a fence of true morality, which entails mindfulness. Through mindfulness, true morality is attained at every moment.
“The currents in the world that flow, Ajita,”
said the Blessed One,
“Are stemmed by means of mindfulness;
Restraint of currents I proclaim,
By understanding they are dammed”
-- Sn 1035 (Nyanamoli, trans)