To me, it doesn`t matter that much if the band changes structure, it`s what they do with the structure, as there is still a huge amount of space to do different things within, and countless songs have used the exact same structures over decades with very different results.
It also seems like every couple of years there is a slightly new take on a certain style of music that allows artists to be hugely successful and build high esteem (even if momentary) while stripping the music down to a core simplicity and featuring a certain sound or technique that becomes trendy.
There are also a number of bands that specialize in having a distinct sound and not straying from it. I can enjoy that, as well as bands that use a varying range of sounds and structures (SID, SuG, MuCC, etc...)
In the same way movies use the same structures with even less variation, relying on the material presented within that structure to do something different. And even then, there are works that stand as landmarks, like Rashomon, and live on with esteem in certain circles, yet, way more people have seen the latest Hollywood Blockbuster, and were entertained by it.
The way we interpret mediums relies on past experiences and the sensibilities developed from them. So the vast majority of people will enjoy the same structure, and the same chord progressions, and things that differ from the norm don`t go down as smoothly, the experience is harder to grasp, and appreciate. There are of course the occasional endearing songs with different mechanics, though a lot of them seem to become popular or connect with an audience due to the way they are still made to sound like the typical structures we expect.
I always try to use different chords and progressions myself, though the vast majority of what you try with Diminished chords without proper resolves etc.... won`t make an actually good song that also connects to an audience unless it resembles the typical sounds and structure as much as possible.
Examples:
BORN - Alterna
I think it`s a great song, though you clearly can`t get a good feel for the landscape of it, and the majority of people will just find it unsettling in terms of it`s changes. Same would go with certain Black Gene songs.
DOG - Matsuri
Love the tune and IIRC it was their most popular single. Uses a less typical timing but still resembles what we are used to, and people who are unaware of time signatures will not notice.
A9
Used a lot of different compositional styles, most of them sound enough like what listeners would expect and still be comfortable with.
FALILV
Still utilize a lot of `mainstream` elements, though go further off the deep end. I think their popularity with most fans is due to both being different, and delivering hooks, catches, and structural points we can enjoy under `light-listening`, in terms of a song that you can just put on and rock out to, instead of being lost in the rapid changes of structure and tempo, etc...
Gackt
Always did things differently (less so lately but that seems to be the direction he wants to go in), and while he had one of the more different sounds, he was also always one of the best at delivering the popular elements of music that made his songs huge hits.
NOCTURNAL BLOODLUST
Became a lot more popular when they started delivering the elements of songs that really resonated with a wider audience, they were never a band that went into uncharted territory, but once they started into the VK arena, they presented the straightforward audio and visual elements that fans still clamor for, and grew in popularity.
UNiTE
For me, this would be the greatest exception in my taste. They have made a large number of different songs (not always changing structure, but other elements), and that was part of what made me a fan, though their last two albums did not deliver this as much, and I have been disappointed. For other bands, this would not be as big of a deal, but they kind of developed that expectation in my mind, and let it down. So I think how you see the songs and artist`s relies greatly on what kind of expectations you have in the first place, and they are not always easy to change. So what does the listener expect?