I personally really despise filler names, especially when it's picked to just "fill in" or they couldn't think of anything else. However I think one-syllable middle names are adorable and can be fresh. I don't believe there will really be a "new" wave of fillers because they will always be the sames, Grace, Faith, Marie, Lynn, Rose, Leigh etc.
For me, each time I hear a filler middle name I cringe, and having one myself I can say how awful it is, especially as a name lover. If you really feel the need to use a filler I suggest going with a double middle to give your child something special, not just something "run of the mill"
I love the name Rose, but it doesn't really fit with my sib-set as a first name, so I would love to use it as a middle. But I hate that Rose is so overused as a middle and so underused as a first. When I see lyn/leigh/faith/grace/hope/rose/marie as a middle I just think the parents gave up after the first name...and if the first isn't very creative, like if they picked a top 10 name, I just roll my eyes. Maybe Emma Rose or Sohpia Grace has some special meaning to them, but to me it's like they just picked whatever was popular at the moment without giving it any thought.
I recently saw a thread that suggested Kismet as a middle and I surprisingly liked it...it's unusual, but familiar, I like that it means Fate/Destiny but without having the stripper-name quality that Fate and Destiny have.
I'm getting really sick of James in the middle spot. Half of the little boys I know have the middle name James. Heck, about a quarter the baby boys on Nameberry get it too. It's a great name, and it flows really well, especially if you're honoring someone, but seriously? The SSA needs to start a list of most popular middle names.
To me, I don't really mind when people give their kids filler middle names. Like above posters said, sometimes the filler name holds meaning & honors family. Also, I agree if the name adds to the flow of the whole name it's serving a purpose.
Since I like first names that are less trendy and more unique, I kind of like the idea of a more conservative sounding middle name (not Ann, Marie, Lynn, Lee, Jane or anything like that though...). Then again, I'm not really one for nature/place names (shrug).
That said, I'm not in love with my own middle which is one of the traditional, common ones. I like it ok because my first and middle names together have a nice meaning.