I'm only responding to the thread title.
Yes trophies are a time sink for obsessive completionists. For everyone else they are something to strive for for a game you really like and want to complete, but more or less ignore for a sub-excellent game.
No they are not used to sell crappy games. Only the truly obsessive must play every game crazy person would buy crappy games to amass more trophies and a butt ton of platinums. The number of these people is too low to materially increase a game's sales.
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
