1575 total potency at the cost of a single Sen, which can be fired off after two GCDs, and grants a stack of meditation is quite possibly one of the biggest utility/damage abilities in the game. SAM is a very symmetrical job, so I honestly don't know what else to make the single Sen other than a DoT, especially one on the level of Higanbana.
It's really not about the simplicity of SAM so much as that both Higanbana and Gokken have enough situations where using them over Setsugekka is the better choice. Plus cone AoE abilities make you evaluate the field for the best target instead of just mindlessly blasting a circular AoE. SAM gets to make use of the majority of its kit no matter what content it is in, and this makes it a really fun job to play. It really is one most well-designed jobs in XIV, and you almost don't want them to even touch it. A good polishing here and there is all it needs.
I think why their DoT might 'feel' awkward is because it isn't on demand, and requires GCDs to not only build it up, but also use it. However, that is also a reason why it also so powerful, and why it contributes so much to interactive and interesting gameplay for SAM.
SAM is a bad example for a job having a cumbersome DoT to worry about. I think that would apply more to jobs that already have plenty of other things to manage, and this heavily involves their own resources and how they build it up. SAM is pretty straight forward in the sense that there isn't a whole lot of decision making involved when it comes to building up their gauges. A lot of jobs sacrifice their GCD windows to build up their gauges when situations call for different abilities to be used, but this doesn't really happen for SAM. The only time their gauges don't build is when they screw up. Things become crafty for the Samurai when it comes to the expenditure of their resources so they maximize their damage without arsing themselves out of 1200+ pot attacks when their burst windows open up.