Point 1. With respect to cosmological models being simply a matter of "gas dynamics and nuclear chemistry", the thermodynamic assumptions implicit in simple gas dynamics are not the traditional equilibrium thermodynamics. There is significant recent developments into non-equilibrium thermodynamics which may not have filtered into the community of cosmologists.
Astrophysicists in general work very closely with physicists involved with physicists that specialize in hydrodynamics, non-equilibrium thermodynamics, and plasma physics, and in a lot of areas (such as the interstellar medium), non-local thermodynamic effects are important. However, as far as I'm aware of, no one has been able to come up with an argument that non-local thermal equilibrium effects are important on cosmological scales.
You can usually figure out whether or not non-LTE effects are important by simple timescale arguments. You calculate the timescale it takes for something to go into thermal equilibrium, and you calculate the timescales that you are looking at. The problem with looking for non-LTE effects in cosmology is that you have billions of years for the gas to go into thermal equilibrium, which makes non-LTE effects hard to justify. It's very hard to get a non-LTE effect while most of the microwave background is close to a black-body.
Now people have been looking at non-LTE effects in big-bang nucleosynthesis for years, and no one has come up with something that would change things enough to cause a major rethink.
Also, in doing this sort of work you want to keep your arguments simple if you can. Simple arguments are easier to deal with. If you have gas that sits around for a million years, it's going to likely be in equilibrium so the behavior of said gas is likely to be simple.
(Might be a good thesis topic!?)
The problem is that you can use some very simple arguments to argue that non-LTE effects aren't important. (Basically, you have billions of years for the gas to reach local thermal equilibrium.) If you can come up with a reason why those arguments are questionable, that's worth an short journal article.
The problem is that if you look at the question, and then you conclude that there is no way that it will work, then that's not publishable. A lot of science is like mining for gold or digging for oil. It's either there or it isn't, and there is no oil there, it doesn't matter how much you dig. You might find something else (i.e. you are looking for gold and find diamonds). No one has ever been able to figure out how to make deuterium, but people *did* figure out that you can make lithium and beryllium through some of these processes.
Point 2. FWIW One shouldn't identify exotic dark matter (e.g. monopoles, super-partners et al) with non-baryonic dark matter which may include non-exotic leptonic matter. If neutrino's have mass then they are indeed WIMPS.
This won't work. The problem with neutrinos is that you can calculate the number of neutrinos from nuclear reactions rates, and for each hydrogen atom, you will have N neutrinos. If the neutrinos have any substantial mass, then the universe would have collapsed billions of years ago. If the neutrinos don't have much mass, then what happens is that they will move energy from dense regions to non-dense regions, and this will wipe out any galaxy structure. It's also that we have limits on the mass of the neutrino, and the experimental limits mean that they don't have enough mass to be WIMPS.
You can get clever (what happens if the neutrinos decay, well we should so some sort of glow, what happens if the nuclear reactions don't produce the necessary neutrinos, well then that means that certain conservations law don't work and that causes other problems). People have been playing this game for about three decades, and it's pretty settled that if the WIMPS are neutrinos, then there is something basically wrong with our understanding of particle and nuclear physics. Again, it's possible that people have missed something, and after reading up on all of the ideas that have been tried, someone comes up with some new and creative idea how WIMPS could be massive neutrinos, then that's worth a journal article.
After thinking about new, clever, and creative ideas for thirty years, people just run out of them. Just to use the gold analogy. Maybe someone did miss a spot, but if you go into a mine and you see holes everywhere and no one has struck gold, then you start thinking that maybe there isn't any gold there, and you should look somewhere else.
And if they are not neutrinos, then there is nothing else in the standard model will work. So if dark matter does exist. it's going to be something we don't understand. Period.
to find the right model.
