There's no reason to be bothered by the naysayers tbh. I wasn't lurking ATRL during 2011 but I distinctly remember that online trolls and haters (specifically little monsters, oh how times have changed
) hated 21 and called it boring, repetitive, the same sound, etc. The whole year of 2011 was Monsters v Daydreamers. It lasted all the way 'til the Grammys 2012 when little monsters were livid that 21 beat BTW for AOTY, because they believed BTW was better because it was "different" while 21 was "boring and the same." Yet out of those two albums, 21 has remained relevant and more noteworthy in the music industry. It's only been five years, but so far, 21 is standing the test of time, not BTW.
The same is occurring this time with 25, the same exact criticisms, except instead of Monsters doing the hating, it's another fanbase that's hating. 25 has its flaws and may not have the same impact 21 had in the music industry, but it goes to show that incessant blind hate shouldn't be taken too seriously.
Adele will probably have the same "she's boring, etc." criticism throughout her career, even if she were to seriously spice things up with her music. And that's fine because that's the case with almost every artist; some artists are called generic their whole career, some are called too gimmicky, others are said "she only writes about her ex's!" And that's all okay, whether those criticisms are true or not.
If she ever covers "Landslide," "The Way We Were," and/or "I Will Always Love You," I think I'll die.