As Warrior said doing good conversions of models is very time consuming, especially MAX models, and in many cases the finasl outcome will never be as good as the original, another point to mention is a LW or MAX model of about 2 to 3MB in size can quite easily become 10 to 15MB when converted into an OBJ file, and there's a lot more to converting a model to OBJ that will work in Poser than you might think, first off Poser turns everything into 100% smooth edges, so a Viper or Raider will end up looking like it's made of marshmallow instead of some kind of metal.
Here's an example, below is my Poser conversion of wjaspers NS Cylon, the actual conversion from MAX to LW took about a week, then setting it up to work in Poser took about a week and a half, the reason for this is obvious from the images.
This is the converted version in Poser
this is without it being converted, you can see the problem.
Also the LW conversion ended up at 4.05mb, the obj file was 14.58mb, a huge difference.
In many cases the time and effort involved in this process is not worth the hassle involved in making the model into another format, that said, when I do get time I will be converting a couple of models here into Poser props, as long as the original owners do not mind of course, but finding the time is another matter, real world stuff and commercial modeling commitments unfortunately take up an awful lot of my time, hence the amount of time it's taking to finish just modeling my version of a TOS Centurion.
I hope this helps explain why many of the models here will not be converted any time soon, at least by myself
Cheers
Billy