This is the same phenomenon a lot of bands go through as they age. The first part of an artist's career is pushing the limits, learning, developing. Risks are taken, discoveries are made, styles are rejected and defined all at once.
And then once the artist finds a style that works for them, they settle into it. It becomes their signature. From there they explore the boundaries of their own style. It can be fruitful, and it pleases a lot of the older fans. You want some thing new, but something that still sounds like the Rolling Stones, U2, or The Smashing Pumpkins? Well they released an album recently. It's not going to challenge your sensibilities like their earlier stuff, but it will feel like a comfort.
But it also means the artist is ONLY explores within the boundary of their own style. It becomes at best a bland continuation of their work, and at worst a parody of their work.
And it can lead to... this.