An anonymous Marvel source speaking with The Daily Superhero claims that Netflix and Disney worked together on their forthcoming slate of Defenders-branded TV series to pick superheroes who could have a high production-value series without spending a ton of money, specifically focusing on heroes with powers that are easy to depict inexpensively onscreen.
Here's the quote, with more analysis at the link above:
"Daredevil has his enhanced sonar because he is blind and is also a martial artist. Iron Fist is a martial artist with a powerful punch. Cage has indestructible skin and superhuman strength. Jones has superhuman strength. The point being is the cost to display all these heroes' powers will be lower than many expect and this means keeping the production budgets low to be able to put together such an ambitious streaming series universe."
This makes sense, and is probably pretty self-evident to fans given words like "street-level," which have been used to describe the relatively inexpensive Arrow as compared to Marvel's Agents of S.H.I.E.L.D., which is assumed to be one of the more expensive series on network TV (salaries notwithstanding, since shows like Two and a Half Men and The Big Bang Theory cost comparably little to actually produce, but the actors are expensive).