It is not so much about new or more extreme kinds of taste but I am very happy that there are more and more sweets with less sugar that still taste good. Sugar used to be over 50% and it is possible to find sweets with <35% sugar now. At least in Germany. 

These days you can get fruit-flavoured candy that tastes significantly better than what I had as a kid in the 90s. (Though I rarely eat it as an adult because it's still mostly sugar).

edit: standard brands of American commercial candy don't seemed to have changed much though and chocolate in general has not improved.

Scattered thoughts:

1. What was innovation like in the 25 years before you were a kid? My mom (probably 25 years older than you) speaks fondly of the candies that were available when she was a kid; I think that's a quite different set of candies than are available now, and my guess would be that the primary innovations between the '70s and '90s would be in preservatives/shelf-life.
2. Candy is primarily aimed at children, who... aren't known for their discerning palates. As a child you're supposed to like sweet and dislike bitter, right? (Because something something poison is bitter and breastmilk is sweet?) My point being that I'd imagine there isn't really demand for flavor innovation, because kids are happy enough to consume the existing ones? 
   1. They do make more flavors of e.g. Starbursts and Skittles than they originally did — although the new flavors are just as artificial-tasting as the old.
   2. It occurs to me that Jelly Belly is quite good with imitating flavors and to some extent textures (did you ever try their Bertie Botts Beans? the dirt flavor was pretty spot-on, complete with grittiness). From their website it looks like they continue putting out new flavors; I haven't kept up with this since I don't really eat candy anymore, but my guess would be they still have a pretty good hit rate. Not sure how this info factors into the whole picture.
3. I'm not sure about texture. I do think novel texture was exciting to me as a kid, but... maybe a wide enough swath of texture-space has already been covered that innovation there is really costly? There really are a huge number of existing sugar-delivery methods — cotton candy, Gushers, Pop Rocks, Tootsie Pops, Pixie Stix, Baby Bottle Pops. In general: hard candies, chewy candies, liquids, powders, crunchy candies, and things that melt in your mouth. What combinations haven't been tried?
4. This listicle about what candies were released when was interesting to me, and gives some insight into modern candy innovation. They mention 'Fudge Brownie M&Ms' (released 2020), and it looks like Snickers continues releasing new things, like 'Snickers Almond Brownie & Dark Chocolate Squares' (August 2021) and 'Snickers Cinnamon Bun' (October 2021). Maybe part of the story is that the innovation is being done by existing brands, and those brands are so strongly associated with their original product that it's hard for the new candies to get uptake? Or maybe there are too many options and people just throw their hands up and are like "I'm just going to get the thing that I'm familiar with!"? Maybe companies are leaning too hard on limited editions & seasonality? Or maybe it's that fudge brownie M&Ms are good, but they're not THAT much of an improvement over regular M&Ms?

I can often find something with hazelnuts in it, which I am a fan of. I think Toffifay started showing up at the local Harding's around 2000.

I think in general, the most innovative candies have been candies that break the norm. I remember a lot of buzz when some gum company made gum wrappers that you could eat with your gum(Cinnaburst?) Nowadays though, it seems like companies don't need to go that far for people to buy their new chocolate/candy, and there are so many flavours and textures they can slap on if people get tired.

Heres a candy not available 25 years ago: Justins peanut butter cups. It's a Reese's with better quality peanut butter, better texture, and better quality chocolate.

But yes it isn't "innovative" it's just an improved version of the same thing. And presumably 25 years ago there were gourmet peanut butter cups somewhere, even if you had to go in person to a shop that made them by hand.

And technically there are many more flavors of m&m and Skittles than previously. Though all the "new" flavors were probably inspired by things that existed 25 years ago.

I wonder what innovation is still possible in this space. Honestly probably a lot, AI Driven robotic systems could custom make items for a particular person (from a library of 3d printer or pick and place compatible base components), taking into account information from A:B testing and that person's taste and previous meals and nutrient goals.