It was a long time coming but it as inevitable. The pace of the slow advance was informed by the need to first establish strong civilian institutions in captured areas by having the Somalis vote in District commissioners and elders councils before declaring areas ALS free.
It worked-the Somalis themselves were exhausted by war and killing and desired nothing more but a complete break form their old history;in almost all cases they cooperated fully with the KDF providing valuable intel often turning on ALS elements themselves. Kismayu could have been seized on day 1 of the invasion but political aspects demanded a different softly softly approach.
The West showed their true colours in the disparaging writeups of their local 'experts.'

Considering the small size, poor condition and inexperience of Kenya’s fighter force, it’s perhaps surprising that the F-5s have been so busy over Somalia. But there are signs that the high operational tempo is taking a toll. Two F-5s reportedly collided and crashed near Kismayo last week. And an F-5 mistakenly bombed Somali refugees at a camp also near Kismayo, reportedly killing five civilians.

http://www.offiziere.ch/?p=6767

Kenya’s air force is notoriously inexperienced and dilapidated, even by the modest standards of East African air arms. The air force possessed roughly 18 U.S.-built F-5 jet fighters dating from the 1970s, two of which have already been destroyed in the Somalia fighting.

http://www.wired.com/dangerroom/2011/11/kenya-tweets-air-raids/

The Wes can't afford to be seen as ineffective onlooker in this episode as their magical role as 'peace and development bringer' would vanish overnight. This informs their hostility to the operation and Somalia,in their eyes is better off as it is. A vacuum for fundamentalism,poverty and piracy which can be cleverly controlled by proxies. For example knowledgeable sources swear there were 2 crews who hijacked the Ukrainian tank ship in 2008. One to deal with press and receive ransom another who actually hijacked the ship-the latter were not Somali.
The KDF elected to use the entire campaign as a real life lab for new weapons and formations;army spec forces,Chinese z9s and APCs,while the Kismayu capture was crowned with an amphibious landing,an exceedingly rare op in Africa,which IIRC,has only been seen in Biafra days.
Anyway,now its stage 2,for S.Somalia aka Jubbaland which is nation building. Our 2 destinies are now largely intertwined.

As expected by informed observers the capture of Kismayu went off without a hitch.On Thursday night an airborne unit,the 40th Ranger Strike Force staged a night low level drop,while a company of KN marines deployed from the sole Landing Ship Personnel, KNS Galana early Friday supported by 4 gunboats and landed on the beaches on 11m rigid inflatables to scant resistance.

http://karanjazplace..com/2012/09/the-significance-of-kismayu-capture.html