I suspect it's because keyboards are so personal for people who type a lot; it's very easy to see a keyboard and think, "That looks great, except that...". For me, when I see a 60% keyboard, I think, "Okay, but I want my damn separate function keys, arrow keys, and at least dedicated page up/down buttons"; when I see a 70% keyboard, I think, "Yeah, like that."
Personally, I'm typing on a Matias Mini Tactile Pro right now, and I suspect my dream keyboard would just be one of these with a design that didn't feel stuck twenty years in the past. I alternate between this and a Vortex Race 3, I think it is, with Cherry MX clears.
My biggest complaint with the Altar I isn't the layout, it's that it has no switch options, and I don't want a linear switch; that alone makes it Not For Me. (I also don't particularly like the choice to make GIANT NUMBERS; the marketing copy talks about being "typographically balanced" and I think, "But is it?") But it looks like a nice keyboard, and kudos to the designer for pulling it off.