I'm like the Armond White of vidya, so I have to disagree with you there.
It almost seems like R* intended these games to be more downbeat. Toni gets shafted by Sal; he doesn't even get the girl in the end. She takes a high-dive out a window. Similarly, Vic keeps trying to go straight, but the universe is conspiring to make him a drug kingpin. Pretty sure his love interest got violently murdered, as well. It's weird.
I've seen people theorize that the reason why LCS and VCS were more dark and tragic compared to Vice City and San Andreas was because the Housers wanted to help condition the fanbase for the more decidedly grimdark direction GTA IV went.