Your standards are too high. You may be tired of Bootstrap sites, but I assure you that the rest of the world isn't and while Bootstrap's particular look/feel may go out of style, the world isn't going to get sick of sites like this just because they're Bootstrap.

When you say something is "unprofessional", you are implicitly making a comparison between it and other companies in the industry. Exec is a new service, but it serves an existing market which includes Craigslist, Angie's List, Zaarly, TaskRabbit, and AskSunday. Despite being an almost- out- of- the- box- Bootstrap design, it is already better than several of those sites!

It's perfectly fine to not like Exec's design! I'm not faulting you for thinking the type is bad (I think you're wrong about "spacing" though) or the colors generic.

What's less fine is "unprofessional". Again: I think that assertion isn't just wrong; it's part of a meme that casts a pall over the whole site, which is chock full of people who would launch services except that they're waiting months and months and months to get "good design" that nobody in the whole world cares about other than a couple loud people on HN.