Quite simply because new material makes up 5 or so songs from a 20-25 song setlist. Given how much Bon Jovi have changed musically over last decade, it is ignorant to assume that everybody who was a fan up until These Days would still be a fan after Lost Highway BUT most of a standard Bon Jovi set is composed of songs from pre-TD.

It forces some fans into buying an album, that they don't necessarily want, just to ensure they get to see the band play their older (better) material live. IMO, album sales and live tours are two separate entities that can mutually benefit each other. However, one should have no 'forced' bearing on the other - where is consumer choice in all of this?

It can actually be perceived as quite a cowardly decision. They remove some of the 'risk' associated with new album sales by adopting the "all-in" pre-sale packages. Not that album sales would have suffered anyway but it is by far the 'safest' way to do it for the band/record company etc.