With bitcoin your biggest concern is security and you tend to invest to that, and not that much to front-end.
we should just declare bootstrap as a de-facto standard for bitcoin web apps and make that a best-practice and a requirement for a security certificate.
i am actually serious about that. it looks good enough and it makes developers spend more time on where it matters. for some users it could also be a good experience since this is the de-facto default UI everyone knows from other sites.