End in Sight:
There is a lot of (in my opinion) confusion about jhana. There is a form of concentration meditation that can be practiced in which one ultimately loses all sense of having a body and all sensory input, and becomes absorbed into a big emotional ball of bliss...this is what commonly passes for jhana, and it has proven (in the pragmatic dharma community) not to be especially useful for much...which is indicated by the fact that very few advanced practitioners practice it or recommend it.
As far as I can see, this is not what the suttas ever talk about, and so it does not surprise me that it appears not to be useful for much.
I agree with End. Jhana means different things to different people, and so there are a lot opinions out there about whether or not it's worth it to learn how to practice jhana.
When I think "Thai Buddhism", I think of the Forest tradition, which was/is very much jhana-friendly. Just read any of the works by the Ajahns (Mun, Lee, Fuang, Maha Boowa, etc.). All were pro-jhana, though their understanding of jhana was much more based on the Pali suttas than the commentaries. But, I know that the Forest tradition isn't the only Thai Buddhism out there, so I can see how it's possible for the teachers you work with to have a different opinion.
Personally, my practice has only benefited from learning and practicing jhana. I can't think of any better way of gaining an appropriate understanding of dependent co-arising, which is the real meat of the Buddha's teaching.
So, if jhana is working for you, keep it up. There's no need to worry about your insight getting derailed on account of learning this skill.