I personally don't like them because they tend to be weapons, which I am growing to dislike weapon add-ons more and more, and they tend to be low quality made by fanboys with little to no experience in modeling and scripting. While it is good for them to try and learn I would prefer such things to be personal projects. Finally, they are unoriginal. A plus I see to the Tier+Tactical thing was how it tried to go new places by creating a weapon for every catergory, similar to my laser guns. The problem with Halo based weapons though, is they arn't really trying to fill any niche unless it is a Halo RP or something of the sort.
I also have never played Halo, yet I do acknowledge the importance it has had on the development of the videogame industry and it has pioneered the use of sounds in videogames as well which I appreciate.