I haven't played SF. But definitely had issues long before then. They feel like Ubisoft to me. Just re-releasing the same games w/ a reskin over and over.
I partly agree, but feel like they've tried to mix it up while staying true to their style of game at times (plus in gaming keeping your 'core' of the game isn't always bad. Lots of people are always happy to see a new Zelda even if they don't mix it up completely each game).
With Skyrim and Fallout 4 I think they were showing signs of some good changes over Oblivion and F3 (though F3 had some neat changes from the Isometric 1/2 such as VATS).
Skyrim improved graphics (particularly for spells which look like shit in Oblivion), got rid of potato faces and felt like it had more personality than ESIV. I'd say the main quest improved substantially, at the detriment of the guilds/factions (stronger in IV).
Fallout 4 tried to to take some cues from 'Mass Effect' , including a voiced MC which would have been better received
if F4's main quest had better writing and dialogue. The companions (Valentine in particular) were vast improved over previous Bethesda games. Finally the power armor changes were a really good and lore appropriate improvement over PA being just 'clothes'. Sadly the main quest is pretty disappointing and the guns in F4 are just junk. Gigantic LARP foam looking things. The settlements get mixed reactions but weren't a bad idea.
Something really seems to have broken after F4. Their pace in development has become a crawl. Their PR reps are absolute amateurs (see some of their responses to SF criticism), they've made multiple attempts to push paid mods. It's like they're intentionally trying to piss off the public.
One area where I'll agree that they're just re-releasing is combat. Bethesda's floaty 'left trigger, right trigger' melee combat hasn't changed from Oblivion through SF in any real capacity and it's not a great system to begin with. They don't need to be a souls game or try and turn Elder Scrolls into the Witcher or Devil May Cry, but it's aged really poorly.