> This is why things like Bootstrap or other frameworks are so popular, they allow a designer or developer to cover 90% of those scenarios and focus on the important things.
You're definitely right, but this IMO this is a broken model.
Most of the times superior web apps and mobile apps are the ones with extremely well curated UX, maybe even featuring a slim UI. OFC is the product is very revolutionary, you can be still successful with trade-offs in UI/UX, but the second one is far more important than the first one, if you have a shining, super cool bootstrap template, but a horrifying UX, people will definitely walk away and never return. If you have a decent UI, but an outstanding UX, they will stay and give you suggestions (implicit and explicits) in how to improve the UI as well.