ADRs are weird .. the restaurants only hold so many people (compared to how many people come to the parks) .. it is no surprise they fill up quickly.
I think the big issues are:
1) Resort guests get a "jump" on the 180 days. If they have a 10 day resort stay they could be making ADRs at 190 days. Unfair? Shrug (it is a nice perk for staying onsite) .. it just makes it frustrating when you get up to make a reservation at the first available second and nothing is available you want.
2) You can make as many reservations (as long as they don't overlap in time too much) as you want with really no penalty .. so the early people (probably because they don't even have their days planned yet) .. just grab as many as they can.
I know this because I just "abused" this this morning.
I just made 4 reservations for my large groups first days. I too was shocked at how little was available .. so I made 4 different ones (1 breakfast at DHS, 1 lunch at Epcot and 2 dinners (1 at Ohana and 1 at BOG). We plan on using only one, (it would be hilarious to have a meal in 3 different parks) but I just want them available as options, especially since I couldn't get the whole group into some of our prime choices. So .. I could cancel these tomorrow .. or I can just hang onto them for 179 days (even though I have no intention of using them (I doubt I will hang onto them that long). So things will open up later .. the problem is you just don't know WHEN they will open up. Someone could cancel 5 weeks from now in the middle of the day. Someone else in my group (with another
MDE account) will probably try and make some reservations too.
3) Having to plan 180 days in advance is just weird. Why a half a year out to decide WHERE you want to eat? I still don't get the reasoning behind this since you can't plan Fast Passes or even know if hours are solid or what special events may be on that day.
Really I think they should just do day of reservations. Or require a deposit WHEN you make the reservation. That could prevent people from just hoarding them.