I think that was a product of the times. The only way to snap the people of the new Republic out of their medieval social structure was to enact some pretty draconian measures. It's like slapping someone across the face to get their attention.
Ataturk's biggest contribution was that he restored confidence to the people of Turkey and allowed them to wield this confidence freely (no occupation by foreign powers). In terms of economy, Ataturk's reforms were incredible. Turkey went from essentially and entirely agrarian base to an economy that had a viable heavy- and light-industry sector. And he did it
without harming the agricultural sector. Even today, Turkey is one of the few nations in the world that can actually feed itself completely with local produce (most other countries have to import to one degree or another). But Turkey also has a very competitive manufacturing industry, and is a world leader in construction. Granted not all of this happened in Ataturk's lifetime, but that shows how effective a leader he really was.
There was supposed to be a movie made about Ataturk, with Banderas playing the role. It was scuttled by pressure from Armenian and Greek lobby groups in the US. The script for the movie was later modified (and not as heavily as one might think) and used for the movie
Alexander.
Turkey is a little peculiar when it comes to 'Islamism'. Islamism in Turkey has its roots in the pious backlash against the secularization of Turkey in the 20s and 30s. Because this backlash was crushed the way it was, it became less of a dispute over the role of religion in Turkish society and more of a struggle for power, which is why Turkey has polarized into the secular and the religious.
Nor is Turkey as homogenously Muslim as you might think. Yes, something like 98-99% of the population is Muslim, but within that you have Sunnis, Shiites, Alevis, Sufis, and a whole plethora of other sub-groups. And some of these groups really don't like each other, Sunnis and Alevis, for instance. It gets even more complicated when people like the Alevis, who are a minority compared to the Sunnis, turn out to be the less conservative group, and thus tend to support the secularists much more than the mainstream Sunnis.
Some were mentioned earlier. CHP is Ataturk's party, and thus the most likely to follow Kemalism to the letter, but you'll note that they've been increasingly marginalized in recent years. They always seem to get about the same percentage of the vote.
As for how the non-Kemalist leaders did, it depends on the leader, and there were quite a few of them.
I'll just quickly run through the ones that white-wolf listed. Adnan Menderes, for instance, was the first non-Kemalist Prime Minister, but he was overthrown by a coup and hanged in 1961 (though posthumously pardoned in 1990, IIRC).
Turgut Ozal was around in the late 1980s and early 1990s (IIRC), and was a Kurd to boot. He was instrumental in opening up the Turkish economy by eliminating trade restrictions aimed at protecting Turkish industries.
Erdogan, as you know, is PM right now. AKP has done very well with regards to the Turkish economy, and it has also done fairly well with the EU-required reforms. With the latter, AKP has been pretty good at changing the mentality of the average person in Turkey. They are viewed with some suspicion, particularly by secularists, but I personally think that the latter (and the army) don't give the Turkish public enough credit. The army and the secular establishment are worried that the public isn't ready for more freedom (like lifting the headscarf ban, for instance), and fear that the mob may do something stupid (a la Islamic Revolution in Iran). I think that there is enough of a secular base in the population that it can balance out the Islamists, and thus am not that concerned. I worry more about the problem of peer pressure in Turkey. Islamist societies (like Iran, Afghanistan, Saudi, etc.) tend to force secular elements to conform to
their norms, and often aren't flexible enough to accept that some people may not want to live the same way as you. There are enough conservatives in Turkey that pressure on the rest of society could be a problem. But Turkey is going to have to take the risk sooner or later, so it might as well be now.
I see it this way: secularism and mild Islamism are like a bride and groom. The tension we see right now in Turkey is nothing more than pre-wedding jitters. Might as well take the plunge. You can always divorce later.