The only demos that really have a reason to be played multiple times are ones that can send save data over (like the new Pokemon Mystery Dungeon or The Denpa Men), but the concept of arbitrary limits is still absurd since nobody else does it.
But good to know it is developers to blame. Since they think people don't buy the games because they are "playing the demos instead" when in fact, it's because the demos make games seem pretty bad. They play it once, hate it, and don't buy it.@Turner4590
You realize most demos (in the real world) come out BEFORE a game is out, so you CAN'T buy it, right?
People complain because there is no reason, and nobody else does it. Not necessarily because they need to.
And like I said above, some games actually use the save data from the demo. So there is legitimately a reason to keep playing those to get things before the game comes out.