It is the most fair because it eliminates (or at the least, greatly diminishes) many of the abuses of the system that take place at 180 days. One being the person who books a ton of ADRs at the the 180 day mark even though they have no resort reservations and it may only be a 25% chance that they actually go on the trip. And then when they decide they're not going, maybe they cancel the ADRs, maybe they don't. At least at 45 days, you know if you're going or not since payment is due. And don't bring up people who stay offsite and how the 45 day mark means nothing to them. Disney should design their system around who is staying with them. Another abuse, obviously, is the multiple bookers (and those of you who think not that many people do this...I've got a bridge I'd like to sell you). With the increased number of people online/on the phone making ADRs if it opened up at 45 days, instead of booking two or three restaurants for the same night, you'd be wiser to just make one and move on to the next night. Plus, everyone's park days would be pretty much decided upon - you can't tell me anyone's park days are set in stone 180 days out. This results in less unused ADRs.
And as for those meals being enjoyed by otheres who deserve them...in many cases they are not. Two weeks ago at the Princess breakfast in Akershus (what the OP is looking for), it was more than half-empty even though there wasn't an ADR to be had - which I know because I tries to amednd our time but there was nothing else available. I saw other restaurants with far too many empty tables, as they were also supposedly fully booked, particulaly Coral Reef and Chef Mickey's.
The system, as currently set up, encourages a lot of abuse of the system. It makes people feel the need to hoard ADRs - many of which go unused.