I don't think it could necessarily hurt you to have a master's, but I wouldn't plan on having one. Also, some people may disagree as there are quality universities with one-year master's programs (I can't speak to the quality OF the M.A. programs), but I don't think you should plan to finish a master's degree in one year unless you've already begun your thesis. About getting an M.A. degree- I don't think anyone would frown upon it, I don't think it would hurt your chances of admission, but I don't think it will shorten your time at the university, which is why it can be a negative thing for you. I know full well that the schools I'm applying to will not accept my master's thesis, and transfer 6 of my 50 units tops.
The only reason I am getting a master's degree is because I did not get accepted into funded Ph.D. programs across the US, I had job offers to be a full-time clinical research coordinator but they were in other states and I was not ~ready~ to move (very family-oriented, had some growing up to do), and I wanted to at least do something in between my bachelor's and reapplying that would advance my knowledge of psychology. I ended up getting a research assistantship and grant funding, so my first year has been free plus a little cash, and I'm applying for a GTA position which will also provide tuition remission and a stipend- it's been free, so why not? I've certainly developed a lot as a professional, I get to see clients (I don't think Ph.D.s care about this one, but it has made me develop a level of professionalism that I didn't have as an undergrad), and I'm working at an advanced level with a great deal of trust from my thesis advisor.
However, if you don't have to do a master's, don't plan on one- it's just tacking two years onto your length of time in school, essentially
long-winded, but take-home message, I would apply them to your bachelor's if you are planning on taking them anyway. That way, you can use those four classes to graduate instead of taking four undergrad classes for units, and taking these four classes for your pleasure and adding them to a master's degree you may not get.