if you like to listen at high volume or even if not so much but you have good recordings with a lot of dynamic range, do not estimate the value of more watts than you think you need until you hear the difference.
I find it almost always pays to date to throw the kitchen sink at most good speakers capable of handling it. I threw 500 w/ch at mine and do not regret it at all. I feel any less would be a step in the wrong direction though still perhaps more than needed normally.
1500 w/ch is much bigger kitchen sink. Why do it? To raise the bar for those who might care and be able to afford the luxury. Its a concrete measurable step forward that is hard to doubt or question compared to many claimed innovations with new products. it unquestionably rasises the bar. To do it in a integrated nonetheless makes it an even grander achievement. The evidence is clear and right before ones eyes. One might still question the value or if needed though. Probably not for most. The price helps assure that.