I used to mod using the creation engine. I loved it. It was incredibly efficient at building big, convincing worlds. Whenever I hear people shit on the engine its always very obvious they have no experience with it. Its surprisingly very user friendly and allows you to customise nearly anything on the fly. Any layman can start building some impressive shit after a few youtube tutorials. I actually think Bethesda should release a game that's a consumer friendly version of their engine. Make it a minecraft type experiance.
Of course there are some major bottlenecks that we continue to see in Bethesda games, but the remedy for that isn't as easy as just saying 'lets make this new game on UE5'. There's so much you have to do to make that transition, especially considering that Bethesda most likely has a work flow they like to follow that is directly informed by how the creation engine functions. Of course this workflow will then inform larger business strategies like funding, deadlines etc. Strategies that are decades in the making.
Personally I think there's nothing wrong with continuing to use the creation engine, they can keep modding it and expanding what they have. My issue with some of these prevalent issues we continue to see is that their design philosophies aren't directly tackling these issues. I think its a problem with their design strategy over their engine. I think if they wanted their engine to function without bugs they could probably do it, but whats a similar theme we continue to see from the industry at large now? Its rushing things to market to save money. I think Bethesda (like so many others) have fallen for the corporatisation of their studio. When a creative company gets too big it becomes near impossible to manage with focus. The answer isn't to throw out the creation engine, the answer is to have government regulation to stop companies selling broken consumer products. Fallout 4 still sold millions despite it releasing like shit. Thats not an engine issue, thats a company issue. The company didn't think it was worth the money to fix their engine because they knew it would sell either way. Starfield will release broken, but it will still make millions and meet projections. The industry is a bloated mess. The creation engine is a fucking cool piece of software