Spending money is a key component of making money. Re-editing and upgrading TNG would be expensive, but it would only involve the post production element. No scripting, directing, filming, acting, set building, production crew etc to pay for. Just the raw film ready for the editor. I'd watch it. Might even buy it if they did to my flavour.
Spending money is only "a key component of making money" if the money that is later received represents a reasonable profit margin over what is spent. Completely overhauling 180 episodes of a television series is not likely to yield a sufficient rate of return to justify the expense -- or, more importantly, to justify spending the money on that project versus a project which would yield a higher rate of return.