Doesn't hurt to ask. Just don't stir the pot and tell others if you get anything.
I would still take the position even if they dont give you extra. It may be different at your store, but I personally feel that the pros outweigh the cons. Yes it is more specialized work and you can seriously negatively impact your store if you don't know what you are doing. However, I never have to worry about hours, have a set schedule with weekends off, and I pretty much am left alone to do my job.
I am considered our district trainer and have heard similar complaints and this is what I tell them. With the modernization changes the salesfloor tms were required to learn more skills to warrant the pay increase. Specialty areas such as receiving and hr were all ready at the level corporate needed us to be at. Yes, it seems that we are getting shafted, but you are getting what few others are getting, which is a specific skillset if you do your job correctly. What you do with it is up to you, but know that you are getting an opportunity that others won't get.
That being said I will be the first in line for a pay increase because I think we are still worth it.