Do people go to Starbucks for good coffee?
I go to Starbucks to do work. I can rent a desk there for a few dollars an hour. I get a reasonable internet connection and for some reason, I can focus there. The coffee is not that great but I regard it as fee.
I believe the reason so many people enjoy it is because Starbuck's espresso is a dark roast with a strong (dare I say bitter) flavor to which, when you add sweet and creamy ingredients to, you can still taste the coffee. That's key. Starbuck's coffee goes well with cream and sugar, if you're into that. It's strong and bold no matter what you do to it.
In my experience as a Barista I've tasted some beautiful, single origin coffee beans, medium roast, they had interesting and varied flavor profiles (sometimes "tea-like") , and they were all delicious as is, black, but it (practically) ruined them if you add cream and sugar.
If someone likes a strong cup of coffee, to which they like to add cream and sugar to, they would typically complain about a light or a medium roast.
Ultimately, people like what they like, and they don't really care why.
You need to broaden your interpretation of what the words 'good coffee' mean.
If you're an Italian purist it means the quality of the bean, where it's bought in from, how it's pressed and then served into the cup.
But you (I'm taking leap here) live in NON-MEDITERRANEAN country. If you do. Here is what 'good coffee' means:
Finding a convenient 'reason' to sit, relax and do nothing with the people you love/care for.
So yes. Starbucks do do 'good coffee'.