Developers moaning about Bootstrap have fallen into the common trap of seeing apps through developers' eyes. Please consider that: 1. Almost no one in the world has heard of Bootstrap. Though it's captured our mindshare as developers, most of our users will not know nor care if the app is Bootstrap or not. 2. The vast majority of web apps still will not be Bootstrap apps. Basically none of the general public will say…
If I haven't heard of it, none of my friends have. Out of the hundreds of people I know, I'd imagine possibly one of them has heard of Bootstrap.
Unless your startup target is web developers, nobody will have any clue what you're using as your UI kit, but they'll be pleased when things are where they normally are.