Why are publisher and developers nowadays so terrible at time estimates.

This game is being delayed for 2 reasons:

a) Incompetence. Miyamoto admitted difficulties with HD developing earlier this gen, so maybe they are still having trouble. The game has been in development since 2011, so it's been years. Should be ready by Holiday 2015 and they need it.

or

b) Competence. Nintendo is wising up and letting the Wii U die its death, and focusing on the NX. Having Zelda be a launch title or launch window title for the NX would be a brilliant move. Just like moving TP from the GC to the Wii was brilliant.

The end result of this mindset:

Development for Link Between Worlds started in 2011, the game released late 2013.

http://www.siliconera.com/2013/04/24/the-legend-of-zelda-a-link-to-the-past-2-has-been-in-the-works-since-2011/

Considering that Ocarina 3D released in the Summer of 2011, we can assume that a bunch of people moved straight onto the development of ALBW and the full team moved onto it shortly after Skyward Sword released in November 2011. A Link Between Worlds was probably in development for over 2 Years time, which fits in with other recent handheld LoZ outings. Phantom Hourglass released mid 2007, Spirit Tracks released late 2009.

Fixed :P 

"A delayed game is eventually good, unless it totally kills your consoles sales,we are sorry Wii U." - Miyamoto

OoT 3D was made by Grezzo and supervised by an unrelated Nintendo EAD studio (the ones behind the first Galaxy).

The Zelda team had no hand in these remakes (besides Aunoma).

"A delayed might lose interest and sales forever; a bad and rushed game could be patched to greatness"- modern video game industry mindset.

Completely agree.

Miyamoto and his philosophies are almost completely irrelevant to the modern gaming industry.