Is it possible that I am using reviews and turns out I have specific things I enjoy or don't enjoy which isn't identical to everyone else?
For example, let's look at some of the highest rated games of all time list and see which ones I've bought and didn't feel I got my money's worth (just looking at the first page of metacritic top all time):
PS3: Assassin's Creed, Rock Band 2 (enjoyed Rock Band 1), Dragon Age: Origins, Call of Duty 4: Modern Warfare,
PC: Bioshock, Diablo 3 (big fan of Diablo 1), StarCraft 2 (big fan of StarCraft 1), Civilization IV.
Of course there are plenty of games where I did get more than my money's worth: Minecraft, Fallout 3, everything by Valve, GTA, WarCraft 3, Diablo, Elder's Scrolls, Baldur's Gate, etc etc. I'd say in any given year, there's probably at least as many games I've bought that were meh and just didn't grab me as there are ones that were amazing. That reminds me, I should probably send another donation to the Dwarf Fortress brothers.
It's not all about reviews, and not all games have demos on launch day (or even weeks later). Fact is, games are high-commitment (hours) and comparatively high-cost.