I buy new consoles on launch so I can start playing whatever is being offered while having the backlog of games from previous console cycles supplement the brunt of my gaming experience until the current gen's catalogue is more fleshed out.
Since I've been buying consoles from the Psx era, I've always had something to play, so I'm never in that, in my opinion, weird category where you find yourself buying a new console and you're relegated to playing 'new' material you've got to buy for it. Nah, you phase it in and with Microsoft honoring their plight to keep Backwards compatibility rolling as smoothly as they can, The new X will be a day one cop with me prolly getting the new Ps whatever 2,3 years later down the line for the exclusives.