Quoted from StevenP:
Simply stated, in freeplay home use, AAB gives you a chance to extend your game, whereas replay merely lets you win meaningless credits or light meaningless specials to give you credits that don't affect your score.
I guess we (you and me) look at it differently. To me, the "Meaningless" credits or specials DO mean something to me just like your high scores mean something to you. In fact, all time High Scores are "meaningless" to ME. Plenty of us "replay" people play our games paying attention to how many credits we "racked up" during a single game. Just like you pay attention to chasing a super high score. Some of us even put our games on Coin Play so we can gauge the value or return for the purchased credit and awarded replays even though they are still technically free. But for us, we perhaps like the idea of a finite limit to how long a game should last or go on. I have said it several times, I consider most AAB games (the ones specifically designed to be AAB only) to be perpetual Hell! Just like many of Today's DMD collectors complain about many Stern games lasting 20 minutes or more to complete a game of 3 balls. EMs were never designed around having marathon games. Early games were designed to be gambling devices. Later, when they were specifically engineered for Amusement and replays, they were designed around a target average game time of 2 1/2 to 3 minutes and a replay award of around 30% (although I have read it stated to be as high as 50%). And as you stated, AAB games were designed for a specific territory to get around very strict coin op laws. They were not the "norm" for any of the manufacturers. If these laws did not exist, neither would the AAB game.
Mr./Mrs. AAB sees two goals in front of him/her on your AAB game: A sequence feature to be completed to light the WOW/Special, and an End of Game High Score. And you get the added benefit of getting additional extra balls as you reach the score thresholds (ie 60K, 120K, 170K) and as you are awarded WOWs on the playfield. Which in all practicality, could allow you to extend your game indefinitely.
Mr./Mrs. Replay sees two goals in front of him/her: A sequence feature to complete to light specials and Score Thresholds to beat to award a Replay. And, if it so matters to him/her (which it really doesn't to me) logging an all time high score.
First off, let me state that no one likes a game that is either too easy or impossible to win/beat. So playing a poorly shopped game is as disappointing as playing a game that ends up being way too easy to continually beat. So yes, games can be set up hard, or easy. And are typically tailored to the owner's ability.
Although it varies from game to game, there are typically two types of AAB ruleset. From how I understand it, most allow you to light the WOW. Once lit, you are allowed to shoot for it. Once you get it, it will only remain lit as long as the ball remains on the playfield. Other games award a WOW upon ball drain and then reset the sequence. Some games award a single WOW and then reset the sequence while the ball is still on the playfield.
For the most part, the Replay counterparts allow you to light the Special which then remains lit until the end of your game (3/5 balls). So, we are limited in the time frame (balls per play) of completing the sequence, and limited on the number of replays we can be awarded (credit wheel limit 5, 10, 15 etc.)
And your comment about it being all about Nostalgic memories or personal sentiment is somewhat funny to me since most "collectors" are doing so for just that reason. If you want to discuss it in the context of operating EM games or even early solid state games, my argument for replay would be even stronger.