It seems like just half of a dbal i2 so I don't get why it costs the same or more in some cases? What am I missing?

Economics of scale.

this OTAL-A?

Why would anyone want a visible laser only for a rifle?

Why not? In a civilian sense, for shooting in akward positions, low light, and with night vision. With a diffuser and on low it gets to about 0.5 watts that is almost invisible, barely detectable but on high it is scortching.. So it fills a lot of roles.
I was wondering though about the cost... The add says it goes deeper. And is more durable than the normal otal, so I'm wondering if it is harder to make or is more durable than the dbal? Maybe it just costs more because it's smaller? Idk

If you have a .mil credentials I HIGHLY reccomend dsg arms there discount is bananas

why not this?

Not sure what the benefit of the OTAL-A is over this if your running NVGs.

For me,vthere is no benefit.. Its just that it's for a sbr, and I don't want anything that big for it, I love the dbal, but for this rifle it is just too much.. Its already pushing it on the weight and space, even the cqbl is too big for it. The otal-a is perfect. I do have a dbal on my 16" though and love it. The laser devices are incredibly robust, there are others that would work but I want the up most reliability, all my stuff on this one are the most durable stuff made. Its my shtf fan one.