I've never really measured how much purchasing power a console gives me before. Thanks for that, OP ... really got me thinking. Well given I have only purchased (including handhelds) 7 different consoles for myself, I would say the modern trend would be if I find, or determine to be confirmed future releases, 5 or more games I'm really intereted in then I will buy a console.
Never understood 'Day 1 purchase' mentality. That being said, I bought relatively late into the PS3 dev cycle and it turned out I was one or two model numbers shy from being able to also play PS2 games so the 'buy late, buy reduced' mentality can bite you in the arse.
Anyways, that .... shitted me, as I have a wealth of awesome PS2 games I play everynow and again (Valkyrie Profile 2: Silmeria, classic Dynasty Warriors, Silent Hill 2, Okami (though better on the Wii)) ... and transporting multiple video game consoles from apartment to apartment is kinda a bother. So I thought; "Hey, buy a PS3 ... then I can put my PS2 into storage and just transport the PS2 games" ... turned out it wasn't the case.
That being said, I have really gotten into the Atelier games recently so I'm not so miffed. I don't know what it is, but I love them.
Some games I love so much I'll buy a console just to play them. Bought a Wii for Metroid Prime 3: Corruption and Skyward Sword, wasn't disappointed. That and Okami really came into its own again on the Wii ...Also got Xenolade Chronicles, The Last Story and Pandora's Tower so I'm not complaining, but all of those game were late in the Wii's lifespan so the Wii really didn't count as having '5+ games that interested me' category apply.
So I do make the occasional exception, but I can't turn down a Zelda game. Though I usually wait, at least, until the console is reduced as much as feasibly possible within a reasonale time span.