If all you want is Apple TV you buy the majority of your videos and so on through Apple then no $99 isn't a ridiculous amount of money but when you buy most of your stuff through other services that all offer devices for less than $50, Amazon, Google, etc, and the only reason you even need Apple TV is for those one or two shows that are only offered by iTunes for example while it may have changed, I haven't checked, at the time I purchased my daughter Lizzie McGuire iTunes was the only service providing that show. Buying a $99 piece of hardware to watch one show that didn't even cost that much to purchase in the first place is yes a ridiculous amount of money.
Honestly when every comparable device that does the exact same things cost so much less then even more so because then it feels like I am not being charged for the product but for the label. I don't care if the label says Apple, Amazon, Google, etc all I care about is being able to watch my shows without having to buy 3 different types of DVD players. That's what it amounts too. I understand Betamax vs VHS and HD vs Blu-Ray those were "Format Wars" so yeah it made sense.
Now we aren't talking about studios doing format wars it's outlet wars. Now they are forcing me to actually have to decide what digital store I will buy my movie at because that previously simple act has now become a game of "which of these stores offers me the widest access to my content.