We always enjoyed MNSSHP (years ago anyway, I've heard it started getting really crowded over the years), but I felt it worked (besides the more hours than the after hours) because a ton of folks were meeting characters or watching parades -- all that made the ride lines bearable -- for the after hours party, I am told they truly limit ticket sales for the after hours events (in the past) which should allow for shorter lines -- I guess my take is that it is a chance to be in the park in the evening hours while getting in a good ride count.
For my family, we are shut out of getting passes, we live real close to WDW -- this MIGHT be better than a day ticket for MY FAMILY especially if AP's do not return as something like this would be our only visit this year -- heck, safe for last year, we've giving the mouse something like a 7 or 8 year break -- I can continue to wait (to ride the 7 dwarfs thing that I saw under construction when we were last Disney AP folks ;-)
Oh, I have heard that fireworks should close the night at MK for day guest (and After Hours guest that are there) as the After Hours events start after MK fireworks (at closing while the party is after closing (assuming fireworks pick back up prior to August).
For the 50th, I guess this is a way for more folks to walk into the MK in OCT -- but I still recall the crap show that was 10/1/11 as being the only time I ever felt my life was in danger at a theme park.