The circumcised penis thrusts hard and bangs in order to generate pleasurable sensations from pressure-sensitive nerves in its shaft and base area.  It needs to focus on stimulating these pressure-responsive nerves in its shaft and base because thousands of touch-sensitive nerves have been removed in its upper area by circumcision.

EXPLANATION IN DETAIL

On the natural penis, nature intended for sexual excitation to take place primarily in the upper penis.  (See Reason #6 Natural Sex, How Nature Intended a Penis to Derive Pleasure)

But circumcision cuts off erotic tissue from the upper penis and this devastates the upper penis pleasure zones.

The circumcised penis, during intercourse, doesn't experience the high level of pleasurable feelings in its upper penis area that the natural penis does. This is to be expected since circumcision removes many thousands of touch-sensitive pleasure nerves and destroys the gliding mechanism that allows nerves time to rest & recharge (by covering them briefly) so they'll fire off strong sensations.

During intercourse, the circ penis's upper area can actually lose feeling as thrusting progresses, and many circ'd men complain of numbness in their upper penis area during intercourse.

The circ penis does notice that its best pleasure emanates from its lower penis area and its base/pubic mound area.

This lower region of the penis has very few touch-sensitive sexual nerves. But it does have many pressure-sensitive pleasure nerves (located within the corpora cavernosum).  Therefore, the circumcised penis thrusts to stimulate the  pressure-sensitive sexual nerves in its lower penis area
and its base/pubic mound area.

These pressure-sensitive nerves are deep inside the shaft and base of the penis, and they require hard, forceful pressure to excite them.  So the circumcised man has to bear down on his thrusts more forcefully to feel pleasure.

Also, these pressure-sensitive nerves in the penis lower region require a longer period of rest & recharge than do the touch-sensitive nerves in the upper penis's foreskin.  Therefore, the circ man uses an elongated thrusting stroke that gives these nerves a longer time to rest & recharge when the penis pulls far outside the vagina.

The circumcised man notices that by using an elongated stroke and repeatedly banging his penis base area against the woman's genitals, he can build up enough erotic feeling to make intercourse pleasurable and come to orgasm.  However, he would have been able to derive the same objective, with probably greater pleasure, if his foreskin were left intact, and he'd not have to subject his female partner to the discomfort and/or pain of hard, bangaway thrusting.

COMMENT FOR A MAN CIRC'D IN ADULTHOOD

Consider the following comments from a man, circumcised in adulthood, who wrote to the author of this website. 

Since I had my penis circumcised:

1) I have lost about 80% of my penis’s sensitivity. 

2) I have no response to my wife’s vaginal movements. 

3) I take so long to reach orgasm that I irritate my wife’s vagina, even though we use lots of lubricant. 

4) She complains that my penis often feels hard and painful now that it lacks the soft skin folds of the foreskin. 

5) My wife can only reach orgasm now with her own hand stimulating her clitoris.

And you are quite right in saying that in sexual intercourse, circumcised men are more rough and tend to pound or bang away, using long thrusts. 
I have found this ever increasingly true about my style since being circumcised.  This is because I now have so little sensitivity, and, thus, no build-up of feeling or response during intercourse that I just pound harder and faster in a desperate hope of reaching orgasm.

SUMMARY: WHY THE CIRC MAN THRUSTS HARD & BANGS

Essentially, the circumcised penis bangs its base area against the woman’s genital region to make up for the pleasuring it isn’t experiencing in its upper area due to its missing foreskin.

It finds forceful banging pleasurable for two reasons:

1) banging causes many pressure-sensitive nerves to fire off simultaneously;  2) many nerves in the base area are deeply set, so strong, forceful pressuring is required to excite them.

Circumcised penis’s use of an elongated stroke adds greater force to its banging action because of the momentum it builds up by withdrawing far out of the vagina and then pile-driving itself inward.