[scott_w]

Funnily enough, this caused issues with PS2 games ported to Xbox subsequently. Metal Gear Solid 2 made heavy use of the pressure sensitive buttons for weapon aiming vs shooting. I recall the Xbox didn't have pressure sensitive buttons, so had to do something different to achieve this (I'd need someone else to fill in the gaps here, I never owned an Xbox!)

[rideontime]

Original Xbox had the pressure-sensitive buttons, but 360 did not, which specifically caused issues for MGS 2 and 3 in the HD Collection. Twin Snakes on the Gamecube suffered similarly, requiring awkward combinations of Y and A to lower your pistol or raise your automatic weapon without firing.

[butlike]

THAT'S WHY. As an avid Metal Gear enthusiast during the release of MGS2, I remember having nearly-impossible time finding MGS2 Substance for PS2 when I wanted to do my first real replay way back in the day. I imagine it was the more popular version since it had working pressure buttons, presumably.

[thunderfork]

The original Xbox actually did have pressure sensitive face buttons. Off the top of my head, the only game I know that used them is Vexx (which strangely didn't use them on the PS2...)