Indeed, the marketing for Solo really fell flat. There are times I wonder if Disney was intentionally writing it off, expecting it to do decent at the box office simply because of the Star Wars brand, but really invested in Avengers or Mary Poppins.
I don’t think negative reception to TLJ had anything to do with Solo’s failure. I think the real problem was like you said, why should audiences watch Solo? The average person’s reaction was likely:
Another Star Wars movie? I mean they’re fun, but wasn’t the last one like 5 months ago?
Wait that’s not Harrison Ford! What’s with this?
This looks generic, nothing special.
No lightsabers this time, huh.
Eh, it looks fine but I don’t feel like watching another movie. Just saw Avengers and Deadpool.
Nailed it.