First, and very simply, the existing Exec design is conspicuously weak and unprofessional. It looks copy+pasted from a million other sites, but without anyone with a good eye to look it over and pull the disparate copied elements together. For all the negative feedback, there should be more acknowledgment that Kyro's decision does a far better job aesthetically and in terms of polish than what exists now.
Second, when did marketing and design become conflated? Most of the criticism is about the approach the designer has taken to writing marketing copy and otherwise persuading people to sign up. Is that really the role of a designer? Maybe it is these days, but I think that means the role has now become a hybrid of two pretty unrelated disciplines.
A great designer takes a sense of experience and branding and translates it into abstraction: color, form, rhythm, etc. Kyro has done a good job of this. The design, text aside, reads as high-end, serious, appealing to professionals, and most importantly like a solid company that is trustworthy and can deliver on its promises.
A great copywriter or marketer is doing a totally different thing, trying to persuade people and get them to convert. From knowing some people who are pretty good at both things, I'm not convinced that these two roles should be turned into one. I think this is a vast improvement on design before I even analyze whether or not its a marketing copy improvement.