Ok, long answer, sorry. Basically, I would approach this issue from less of a “will your application fees be wasted” perspective and more of a “what makes the most sense for you” perspective.
I think the first thing to consider is, MA aside, whether or not you have the other necessary components of a PhD application: a detailed, compelling, this-research-is-absolutely-vital-and-simply-must-be-undertaken-and-especially-by-me project proposal, three enthusiastic letters of reference, and an excellent writing sample of an appropriate length. If you think the only thing potentially stopping you from getting into a PhD program is the nominal lack of an MA degree, you might as well apply to a number of PhD programs and MA programs and see what happens. Some departments may offer you MA admission anyway if you apply for the PhD but they think you're better suited for an MA, so your applications ultimately wouldn't be wasted. (Of course, these applied-to-PhD-but-accepted-to-MA situations are hardly relevant if the MA costs millions of dollars and is unfunded, lol).
Personally, however, I did not have all of the above components until after I completed my MA, and the one component I might have had—the three good letters of reference—was markedly strengthened after I’d finished my MA and all of my letter writers had had the chance to read my finished thesis and work with me for a longer period of time. It also meant I had letter writers from two institutions, as opposed to just my undergraduate institution. I'm not saying my situation is universal, though: for instance, you’re already writing an honours thesis in your undergrad program, which has given you a chance to develop and demonstrate your research interests as well as produce a writing sample. This wasn’t an opportunity offered in my undergrad program. Also—although I’m admittedly kind of an extreme in this regard—I wasn’t even committed to a specific field/era/approach until after my MA! You, conversely, seem as though you are, and you also have the language skills to back your interest up.
In a less instrumental sense, however, doing an MA offered me a variety of experiences and opportunities that allowed me to grow as both a scholar and a person (moved to a new city, met so many new people, experienced a new art history department with different theoretical concerns and pedagogical approaches, saw new museums and collections, etc.). I published some of my seminar papers (if only in grad journals) and started working on a more significant academic publication. Even aside from the fact that I wouldn’t have had the portfolio to get into a PhD program before the MA, I wouldn’t have wanted to forgo the MA and its nature as a new, unique experience unto itself. I’m currently working at a museum in the year between my MA and PhD, and that, too, has been a meaningful opportunity to develop skills, confidence, and connections as well as to spend another year back in the city in which I did my undergrad.
Obviously, though, there are other factors here, which, again, may or may not apply to you: I didn’t spend any money to do my MA, for instance, so it wasn’t a loss in that regard; I’ve hardly travelled (for financial reasons), so I welcomed the chance to spend a short period of time somewhere new; and (maybe most importantly) while I was academically successful in my undergrad, I suffered from a severe lack of confidence, and I was, frankly, just not ready to be a PhD student with, e.g., undergraduate teaching responsibilities.
In short, my MA was critical in terms of both academic experience and life experience, but the personal factors involved in this decision are known to you alone. I knew when I wasn’t ready, and I also knew when I was. If you feel unsure, you might start by talking to a professor you trust (your thesis supervisor, probably—someone who will be honest and critique you openly when necessary) to get their opinion on whether the project you’d want to propose for your PhD is “good enough," and go from there.
Good luck!